Direct-drive system for cooling system fans, exhaust blowers and pumps

ABSTRACT

The present invention is directed to a load bearing direct-drive system and a variable process control system for efficiently managing the operation of fans in a cooling system such as a wet-cooling tower, air-cooled heat exchanger (ACHE), HVAC system, blowers and centrifugal blowers, mechanical towers or chiller systems. In one embodiment, the load bearing direct-drive system comprises a load bearing torque multiplier device having an output rotatable shaft connected to a fan, and a load bearing motor comprising a rotatable shaft that drives the load bearing torque multiplier device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser.No. 14/766,239, filed Aug. 6, 2015 which is the National Stage ofInternational Application No. PCT/US2014/014408, filed Feb. 3, 2014which claims the benefit of U.S. provisional application No. 61/762,891,filed Feb. 9, 2013. The disclosures of application Ser. Nos. 14/766,239,PCT/US2014/014408 and 61/762,891 are hereby incorporated by referenceherein in their entireties.

TECHNICAL FIELD

The present invention generally relates to a method and system forefficiently managing the operation and performance of cooling towers,air-cooled heat exchangers (ACHE), HVAC systems, mechanical towers,chillers, exhaust blowers and pumps.

BACKGROUND ART

Industrial cooling systems, such as wet-cooling towers and air-cooledheat exchangers (ACHE), are used to remove the heat absorbed incirculating cooling water used in power plants, petroleum refineries,petrochemical and chemical plants, natural gas processing plants andother industrial facilities. Wet-cooling towers and ACHEs are widelyused in the petroleum refining industry. Refining of petroleum dependsupon the cooling function provided by the wet-cooling towers andair-cooled heat exchangers. Refineries process hydrocarbons at hightemperatures and pressures using processes such as Liquid CatalyticCracking and Isomerization. Cooling water is used to control operatingtemperatures and pressures. The loss of cooling water circulation withina refinery can lead to unstable and dangerous operating conditionsrequiring an immediate shut down of processing units. Wet-cooling towersand ACHEs have become “mission critical assets” for petroleum refineryproduction. Thus, cooling reliability has become mission critical torefinery safety and profit and is affected by many factors such asenvironmental limitations on cooling water usage, environmental permitsand inelastic supply chain pressures and variable refining margins. Asdemand for high-end products such as automotive and aviation fuel hasrisen and refining capacity has shrunk, the refineries have incorporatedmany new processes that extract hydrogen from the lower valueby-products and recombined them into the higher value products. Theseprocesses are dependent on cooling to optimize the yield and quality ofthe product. Over the past decade, many refineries have been addingprocesses that reform low grade petroleum products into higher grade andmore profitable products such as aviation and automotive gasoline. Theseprocesses are highly dependent upon the wet-cooling towers and ACHEs tocontrol the process temperatures and pressures that affect the productquality, process yield and safety of the process. In addition, theseprocesses have tapped a great deal of the cooling capacity reserve inthe towers leaving some refineries “cooling limited” on hot days andeven bottlenecked. ACHE cooling differs from wet cooling towers in thatACHEs depend on air for air cooling as opposed to the latent heat ofvaporization or “evaporative cooling”. Most U.S. refineries operate wellabove 90% capacity and thus, uninterrupted refinery operation iscritical to refinery profit and paying for the process upgradesimplemented over the last decade. The effect of the interruption in theoperation of cooling units with respect to the impact of petroleumproduct prices is described in the report entitled “Refinery Outages:Description and Potential Impact On Petroleum Product Prices”, March2007, U.S. Department of Energy.

Typically, a wet cooling tower system comprises a basin which holdscooling water that is routed through the heat exchangers and condensersin an industrial facility. The cool water absorbs heat from the hotprocess streams that need to be cooled or condensed, and the absorbedheat warms the circulating water. The warm circulating water isdelivered to the top of the cooling tower and trickles downward overfill material inside the tower. The fill material is configured toprovide a maximum contact surface, and maximum contact time, between thewater and air. The air-to-water ratio in a wet cooling tower is known asthe L/G ratio. As the water trickles downward over the fill material, itcontacts ambient air rising up through the tower either by natural draftor by forced draft using large fans in the tower. Many wet coolingtowers comprise a plurality of cells in which the cooling of water takesplace in each cell in accordance with the foregoing technique. Coolingtowers are described extensively in the treatise entitled “Cooling TowerFundamentals”, second edition, 2006, edited by John C. Hensley,published by SPX Cooling Technologies, Inc.

Many wet cooling towers in use today utilize large fans, as described inthe foregoing discussion, to provide the ambient air. The fans areenclosed within a fan stack which is located on the fan deck of thecooling tower. Fan stacks are typically configured to have a parabolicshape to seal the fan and add fan velocity recovery. In other systems,the fan stack may have a cylindrical shape. Drive systems are used todrive and rotate the fans. The efficiency and production rate of acooling tower is heavily dependent upon the reliability of the fan drivesystem. The duty cycle required of the fan drive system in a coolingtower environment is extreme due to intense humidity, poor waterchemistry, potentially explosive gases and icing conditions, wind shearforces, corrosive water treatment chemicals, and demanding mechanicaldrive requirements from mechanical and aeromechanical loads fromlarge-diameter fans. In a multi-cell cooling tower, such as the typecommonly used in the petroleum industry, there is a fan and fan drivesystem associated with each cell. Thus, if there is a shutdown of themechanical fan drive system associated with a particular cell, then thatcell suffers a “cell outage”. A cell outage will result in a decrease inthe production of refined petroleum. For example, a “cell outage”lasting for only one day can result in the loss of thousands of refinedbarrels of petroleum. As more cell outages occur within a given timeframe, the percent loss in total tower-cooling potential will increase.This, in turn, will decrease product output and profitability of therefinery and cause an increase in the cost of the refined product to theend user. It is not uncommon for decreases in the output of petroleumrefineries, even if slight, to cause an increase in the cost of gasolineto consumers. There is a direct relationship between cooling BTUs andProduction in barrels per day (BBL/Day).

One prior art drive system commonly used in wet-cooling towers is acomplex, mechanical fan drive system. This type of prior art fan drivesystem utilizes a motor that drives a drive train. The drive train iscoupled to a gearbox, gear-reducer or speed-reducer which is coupled toand drives the fan blades. Referring to FIG. 1, there is shown a portionof a wet-cooling tower 1. Wet-cooling tower 1 utilizes the aforesaidprior art fan drive system. Wet cooling tower 1 has fan stack 2 and fan3. Fan 3 has fan seal disk 4, fan hub 5A and fan blades 5B. Fan blades5B are connected to fan hub 5A. The prior art fan drive system includesa gearbox 6 that is coupled to drive shaft 7 which drives gearbox 6. Theprior art fan drive system includes induction motor 8 which rotatesdrive shaft 7. Shaft couplings, not shown but well known in the art, areat both ends of drive shaft 7. These shaft couplings couple the draftshaft 7 to the gearbox 6 and to induction motor 8. Wet-cooling tower 1includes fan deck 9 upon which sits the fan stack 2. Gearbox 6 andinduction motor 9 are supported by a ladder frame or torque tube (notshown) but which are well known in the art. Vibration switches aretypically located on the ladder frame or torque tube. One such vibrationswitch is vibration switch 8A shown in FIG. 1. These vibration switchesfunction to automatically shut down a fan that has become imbalanced forsome reason. This prior art fan drive system is subject to frequentoutages, a less-than-desirable MTBF (Mean Time Between Failure), andrequires diligent maintenance, such as regular oil changes in hazardousand explosive environments, in order to operate effectively. Couplingand shaft alignment are critical and require experienced craft labor.One common type of prior art mechanical drive system is a single speedgearbox-type fan drive that utilizes five rotating shafts, eightbearings, three shaft seals (two at high speed), and four gears (twomeshes). This drive train absorbs about 3% of the total power. Althoughthis particular prior art fan drive system may have an attractiveinitial low cost, cooling tower end-users found it necessary to purchaseheavy duty and oversized components such as composite gearbox shafts andcouplings in order to prevent breakage of the fan drive componentsespecially when attempting across-the-line starts. Many cooling towerend-users also added other options such as low-oil shutdown,anti-reverse clutches and oil bath heaters. Thus, the life cycle cost ofthe prior art mechanical fan drive system compared to its initialpurchase price is not equitable. Once the end user has purchased themore expensive heavy duty and oversized components, the reliability ofthe prior art fan drive system is still quite poor even after theyperform all the expensive and time consuming maintenance. Thus, thisprior art gearbox-type drive system has a low, initial cost, but a highlife cycle cost with poor reliability. In a multi-cell cooling tower,such as the type commonly used in the petroleum industry, there is a fanand prior art mechanical fan drive system associated with each cell.Thus, if there is a shutdown of the mechanical fan drive systemassociated with a particular cell, then that cell suffers a “celloutage” which was described in the foregoing description. The loss inproductivity over a period of time due to the poor reliability of theprior art mechanical fan drive systems can be measured as a percent lossin refinery production (bbls/day). In one currently operating coolingtower system, data and analysis has shown that the loss of one cell isequated to the loss of 2,000 barrels per day.

Other types of prior art fan drive systems, such as V-belt drivesystems, also exhibit many problems with respect to maintenance, MTBFand performance and do not overcome or eliminate the problems associatedwith the prior art gearbox-type fan drive systems. One attempt toeliminate the problems associated with the prior art gearbox-type fandrive system was the prior art hydraulically driven fan systems. Such asystem is described in U.S. Pat. No. 4,955,585 entitled “HydraulicallyDriven fan System for Water Cooling Tower”.

Air Cooled Heat Exchangers (ACHE) are well known in the art and are usedfor cooling in a variety of industries including power plants, petroleumrefineries, petrochemical and chemical plants, natural gas processingplants, and other industrial facilities that implement energy intensiveprocesses. ACHE exchangers are used typically where there is lack ofwater, or when water-usage permits cannot be obtained. ACHEs lack thecooling effectiveness of “Wet Towers” when compared by size (a.k.a.footprint). Typically, an ACHE uses a finned-tube bundle. Cooling air isprovided by one or more large fans. Usually, the air blows upwardsthrough a horizontal tube bundle. The fans can be either forced orinduced draft, depending on whether the air is pushed or pulled throughthe tube bundle. Similar to wet cooling towers, fan-tip speed typicallydoes not exceed 12,000 feet per minute for aeromechanical reasons andmay be reduced to obtain lower noise levels. The space between thefan(s) and the tube bundle is enclosed by a fan stack that directs theair (flow field) over the tube bundle assembly thereby providingcooling. The whole assembly is usually mounted on legs or a pipe rack.The fans are usually driven by a fan drive assembly that uses anelectric motor. The fan drive assembly is supported by a steel,mechanical drive support system. Vibration switches are typicallylocated on the structure that supports the fan assembly. These vibrationswitches function to automatically shut down a fan that has becomeimbalanced for some reason. Airflow is very important in ACHE cooling toensure that the air has the proper “flow field” and velocity to maximizecooling. Turbulence caused by current fan gear support structure canimpair cooling efficiency. Therefore, mass airflow is the key parameterto removing heat from the tube and bundle system. ACHE cooling differsfrom wet cooling towers in that ACHE cooling is “Convection Cooling” asopposed to the latent heat of vaporization or “evaporative cooling”.

Prior art ACHE fan drive systems use any one of a variety of fan drivecomponents. Examples of such components include electric motors, steamturbines, gas or gasoline engines, or hydraulic motors. The most commondrive device is the electric motor. Steam and gas drive systems havebeen used when electric power is not available. Hydraulic motors havealso been used with limited success. Specifically, although hydraulicmotors provide variable speed control, they have relatively lowefficiencies. Furthermore, similar to prior art gearboxes, hydraulicmotors are prone to leaks which can contaminate the cooling water andrequire environmental remediation. Motor and fan speed are sometimescontrolled with variable frequency drives with mixed success. The mostcommonly used speed reducer is the high-torque, positive type beltdrive, which uses sprockets that mesh with the timing belt cogs. Theyare used with motors up to 50 or 60 horsepower, and with fans up toabout 18 feet in diameter. Banded V-belts are still often used in smallto medium sized fans, and gear drives are used with very large motorsand fan diameters. Fan speed is set by using a proper combination ofsprocket or sheave sizes with timing belts or V-belts, and by selectinga proper reduction ratio with gears. In many instances, right-angle gearboxes are used as part of the fan drive system in order to reduce thespeed of the induction motor and magnify torque from an offsetelectrical motor. However, belt drives, pulleys and right-angle gearboxes have poor reliability. The aforesaid complex, prior art mechanicaldrive systems require stringent maintenance practices to achieveacceptable levels of reliability. In particular, one significant problemwith ACHE fan systems is the poor reliability of the belt due to belttension. A common practice is to upgrade to “timing belts” and add atension system. One technical paper, entitled “Application ofReliability Tools to Improve V-Belt Life on Fin Fan Cooler Units”, byRahadian Bayu of PT, Chevron Pacific Indonesia, Riau, Indonesia,presented at the 2007 International Applied Reliability Symposium,addresses the reliability and efficiency of V-belts used in many priorart fan drive systems. The reliability deficiencies of the belt andpulley systems and the gear reducer systems used in the ACHE fan drivesystems often result in outages that are detrimental to mission criticalindustries such as petroleum refining, petro-chemical, power generationand other process intensive industries dependent on cooling.Furthermore, the motor systems used in the ACHE fan drive systems arecomplex with multiple bearings, auxiliary oil and lubrications systems,complex valve systems for control and operation, and reciprocating partsthat must be replaced at regular intervals. Many petroleum refineries,power plants, petrochemical facilities, chemical plants and otherindustrial facilities utilizing prior art ACHE fan drive systems havereported that poor reliability of belt drive systems and right-angledrive systems has negatively affected production output. Theseindustries have also found that service and maintenance of the beltdrive and gearbox system are major expenditures in the life cycle cost,and that the prior art motors have experienced failure due to theincorrect use of high pressure water spray. The duty cycle required ofan ACHE fan drive system is extreme due to intense humidity, dirt andicing conditions, wind shear forces, water washing (because the motorsare not sealed, sometime they get sprayed by operators to improvecooling on hot days), and demanding mechanical drive requirements.

In an attempt to increase the cooling performance of ACHE coolingsystems, some end-users spray water directly on the ACHE system toprovide additional cooling on process limiting, hot days. Furthermore,since fan blades can become “fouled” or dirty in regular service andlose performance, many end-users water-wash their ACHE system tomaintain their cooling performance. However, directly exposing the ACHEsystem to high pressure water spray can lead to premature maintenanceand/or failure of system components, especially since lubricationsystems are open to the environment and not sealed thereby allowingpenetration by water and other liquids. Thus, the efficiency andproduction rate of a process is heavily dependent upon the reliabilityof the ACHE cooling system and its ability to remove heat from thesystem.

Prior art single-speed fan drive systems have further drawbacks. Onesuch drawback is that the fan is continuously operated at 100% speedwhich promotes icing of the cooling tower on cold days. Another drawbackis “fan windmilling” which occurs when the fan turns in reverse due tothe updraft force of the tower on the pitch of the fan. Prior art fandrive systems utilizing gearboxes do not allow windmilling due to thelubrication limitations of the gearboxes in reverse and, in most cases,incorporate anti-reverse mechanisms in the gearboxes.

Some prior art variable speed induction motors are programmed to bereactive to basin temperature and respond by raising the fan to 100% fantip speed until basin temperature demand is met and then reducing thespeed to a predetermined set speed which is typically 85% fan tip speed.Such systems utilize lagging feedback loops that result in fan speedoscillation, instability and speed hunting which consume large amountsof energy during abrupt speed changes and inertial changes which resultsin premature wear and failure of gear train parts that are designed forsingle speed, omni-direction operation.

In prior art variable speed fan systems, the fan speed is controlled bythe basin temperature set point. This means that fan speed will increaseaccording to a set algorithm when the basin temperature exceeds atemperature set point in order to cool the basin water. Once the basintemperature set point has been satisfied the fan speed will be reducedaccording to the programmed algorithms. Furthermore, motors andgearboxes are applied without knowledge of the cooling tower thermalperformance and operate only as a function of the basin temperature setpoint which results in large speed swings of the fan wherein the fanspeed is cycled from minimum fan speed to maximum fan speed over a shortperiod of time. The speed swings that occur at maximum fan accelerationconsume significant amounts of energy.

Typical prior art gearboxes are designed for one-way rotation asevidenced by the lube system and gear mesh design. These gearboxes werenever intended to work in reverse. In order to achieve reverse rotation,prior art gearboxes were modified to include additional lube pumps inorder to lubricate in reverse due to the design of the oil slingerlubrication system which is designed to work in only one direction.These lube pumps are typically electric but can also be of otherdesigns. The gear mesh of the gearbox is also a limiting factor forreverse rotation as the loading on the gear mesh is not able to bear thedesign load in reverse as it can in forward rotation. Typically, themodified gearboxes could operate in reverse at slow speed for no morethan two minutes. End users in colder climates that require reverserotation for de-icing the cooling tower on cold days have reportednumerous failures of the gearbox drive train system and secondary damageincluding collapse of the cooling tower. In addition, most operatorshave to manually reverse the system on each cell which may include anelectrician. Since the gearbox and lubrication system are designed forone-way rotation typically at 100% fan speed, fan braking, gear traininertia and variable speed duty will accelerate wear and tear on thegearbox, drive shaft and coupling components as the inertial loads aredirectly reacted into the drive train, gearbox and motor.

Even with the addition of a lubrication pump, prior art gearboxes arelimited to very slow speeds and are limited to a typical duration of nomore than two minutes in reverse operation due to the bearing design.For most cooling towers, the fans operate continuously at 100% fanspeed. In colder weather, the additional cooling resulting from the fansoperating at 100% fan speed actually causes the cooling tower to freezewhich can lead to collapse of the tower. One prior art techniqueutilized by cooling tower operators is the use of two-speed motors todrive the fans. With such a prior art configuration, the two-speed motoris continually jogged in a forward rotation and in a reverse rotation inthe hopes of de-icing the tower. In some cases, the gearboxes areoperated beyond the two minute interval in order to perform de-icing.However, such a technique results in gearbox failure as well as icingdamage to the tower. If the motors are shut off to minimize freezing ofthe towers, the fan and its mechanical system will ice and freeze.Another prior art technique is to de-ice the towers late at night withfire hoses that draw water from the cooling tower basin. However, thisis a dangerous practice and often leads to injuries to personnel.

Variable Speed Fan systems have not been widely adopted. However, in theinterest of energy savings, more VFDs have been applied to inductionmotors and fan gearbox systems with the hope of saving energy. However,these modifications require installation of invertor rated motors andmore robust fan gearbox systems to account for inertial loading forwhich the system was never designed. The DOE (Department of Energy)reports that the average energy savings of such applications is 27%.This savings is directly proportional to the fan laws as opposed tomotor efficiency, which for an induction motor, drops off significantlyin part-load operation.

Currently operating cooling towers typically do not use expensivecondition-monitoring equipment that has questionable reliability andwhich has not been widely accepted by the end users. Vibration safety inprior art fan systems is typically achieved by the placement ofvibration switches on the ladder frame near the motor. An example ofsuch a vibration switch is vibration switch 8A shown in FIG. 1. Thesevibration switches are isolated devices and are simply on-off switchesthat do not provide any kind of external signals or monitoring. Thesevibration switches have poor reliability and are poorly applied andmaintained. Thus, these vibration switches provide no signals orinformation with respect to fan system integrity. Therefore, it is notpossible to determine the source or cause of the vibrations. Suchvibration switches are also vulnerable to malfunction or poorperformance and require frequent testing to assure they are working. Thepoor reliability of these switches and their lack of fidelity to sensean impeding blade failure continues to be a safety issue. In alternateconfigurations, vibration switches have been installed on or in thegearbox itself. However, such vibration sensors also lack the vibrationsignal fidelity and filtering required to perform condition monitoringand system shutdown if needed. Prior art fan balancing typicallyconsists of static balancing done at installation.

In prior art multi-cell cooling systems that utilize a plurality fanswith gearbox drives, each fan is operated independently at 100%, orvariable speed controlled independently by the same algorithm. Coolingtowers are typically designed at one design point: maximum hot daytemperature, maximum wet-bulb temperature. Thus, these cooling towersoperate the fans at 100% steady state to satisfy the maximum hot daytemperature, maximum wet-bulb temperature design condition, regardlessof environmental conditions and process load.

Current practice (Cooling Tower Institute and American Society ofMechanical Engineers) attempts to measure the cooling tower performanceto a precision that is considered impractical for an operating systemthat is constantly changing with the surrounding temperature andwet-bulb temperature. Most refinery operators operate without anymeasure of performance and therefore wait too long between service andmaintenance intervals to correct and restore the performance of thecooling tower. It is not uncommon for some end-users to operate thetower to failure. Some end-users test their cooling towers forperformance on a periodic basis, typically when a cooling tower isexhibiting some type of cooling performance problem. Such tests can beexpensive and time consuming and typically normalize the test data tothe tower design curve. Furthermore, these tests do not provide anytrending data (multiple test points), load data or long-term data toestablish performance, maintenance and service criteria. For example,excessive and wasted energy consumption occurs when the cooling towerfill is clogged. When the cooling tower fill is clogged, the coolingtower fans do not perform effectively because only partial airflow isallowed through the clogged fill. Poor cooling performance results indegraded product quality and/or throughput because reduced cooling isnegatively affecting the process. Poor cooling tower performance canresult in unscheduled downtime and interruptions in production. In manyprior art systems, it is not uncommon for end-users to incorrectlyoperate the cooling tower system by significantly increasing electricalpower to the fan motors to compensate for a clogged tower or to increasethe water flow into the tower to increase cooling when the actualcorrective action is to replace the fill in the tower. Poor coolingtower performance can lead to incorrect operation and has many negativeside effects such as reduced cooling capability, poor reliability,excessive energy consumption, poor plant performance, decrease inproduction and collapse of fill or total structural failure.

Therefore, in order to prevent supply interruption of the inelasticsupply chain of refined petroleum products, the reliability andsubsequent performance of variable load wet-cooling towers and ACHEcooling systems must be improved and managed as a key asset to refinerysafety, production and profit.

World industrialization is accelerating the demand for HVAC. Demand isexpected to increase as developing countries add new infrastructure andper capita income grows while established markets invest in more energyefficient HVAC systems with environmentally friendly refrigerants tocomply with recent regulations and enjoy financial incentives. Sportscomplexes, office buildings, malls and sky scrapers are investing inIntelligent Building Systems that actively manage and monitor thebuildings for heating, cooling and humidity in dynamic weatherconditions. Occupant health, safety and comfort as well as building andequipment integrity are directly related to a properly operating HVACsystem. However, many HVAC systems utilize centrifugal fans which haveless than desirable performance, balance, noise level and energyefficiency.

What is needed is a direct-drive, load bearing system for fans and pumpsthat eliminates the problems and inefficiencies of prior art drivesystems.

DISCLOSURE OF THE INVENTION

The present invention is directed to a load bearing, direct-drive systemthat comprises a motor (or other prime driver) and a torque multiplierdevice. The load bearing, direct-drive system can drive all types offans and pumps used in any application. The load bearing, direct drivesystem of the present invention eliminates the problems andinefficiencies of prior art gear motor drive systems and prior artgearbox drive systems that use multiple components such as shafts,couplings, and expensive gears that comprise complex drive trains andnumerous other components. Some of these prior art drive systems utilizeoil bath lubrication systems which prohibit the mounting of these priorart drive systems in certain positions or angular orientations. The loadbearing, direct drive system of the present invention is a sealed systemand does not use an oil bath lubrication system thereby allowing theload bearing, direct-drive system to be mounted in any position andangular orientation. The load bearing, direct-drive system of thepresent invention can also be used to drive impellers and propellers.

The present invention is directed to a system and method for efficientlymanaging the operation of fans in a cooling tower system includingwet-cooling towers, or air-cooled heat exchanger (ACHE) and blowers. Thepresent invention is also applicable to managing the operation of fansin HVAC systems, mechanical towers, chillers and blowers. The presentinvention is based on the integration of the key features andcharacteristics such as (1) tower thermal performance, (2) fan speed andairflow, (3) motor torque, (4) fan pitch, (5) fan speed, (6) fanaerodynamic properties, and (7) pump flow.

The present invention is directed to a direct-drive system and variableprocess control system for efficiently operating a fan and pumps in awet-cooling tower or air-cooled heat exchanger (ACHE), HVAC system,mechanical tower, chillers or blowers. In one embodiment, thedirect-drive system of the present invention comprises a torquemultiplier device and a permanent magnet motor which drives the torquemultiplier device. In another embodiment, the direct-drive systemcomprises a torque multiplier device and an induction motor which drivesthe torque multiplier device. In a preferred embodiment, the torquemultiplier device comprises an epicyclic traction drive system. Indifferent embodiments described herein, a variable frequency drivedevice may be used with the induction motor and the permanent magnetmotor. Many other embodiments of the direct-drive system of the presentinvention are described herein.

The direct-drive systems of the present invention maintain currentinstallation envelope and interfaces to existing fans without anauxiliary cooling system or apparatus

The present invention is based on the integration of the keycharacteristics such as tower thermal performance, fan speed andairflow, direct-drive system torque, fan pitch, fan speed, fanaerodynamic properties, and pump flow rate. As used herein, the term“pump flow rate” refers to the flow rate of cooled process liquids thatare pumped from the cooling tower for input into an intermediate device,such as condenser, and then to the process, then back to theintermediate device and then back to the cooling tower. The presentinvention uses a variable process control system wherein feedbacksignals from multiple locations are processed in order to control thedirect-drive systems that drive the fans and pumps. Such feedbacksignals represent certain operating conditions including motortemperature, basin temperature, vibrations and pump flow-rate. Thus, thevariable process control system continually adjust the RPM (rotationalspeed or Rotations Per Minute) of the direct-drive systems, and hencefan and pump RPM, as the operators or users change or vary turbineback-pressure set point, condenser temperature set point process signal(e.g. crude cracker), and plant part-load setting. Such operationalfeatures increase cooling when needed, such as cracking crude, and alsosave significant amounts of energy during plant part-load conditions.The variable process control processes these feedback signals tooptimize the plant for cooling and to prevent equipment (turbine)failure or trip. The variable process control alerts the operators forthe need to conduct maintenance actions to remedy deficient operatingconditions such as condenser fouling.

The variable process control system of the present invention comprises acomputer system. The computer system comprises a data acquisitiondevice, (DAQ) and an industrial computer. The data acquisition device(DAQ) and industrial computer are separate devices and are in electronicdata signal communication with each other. The variable process controlsystem of the present invention includes a plurality of variable speedpumps. The variable process control system further comprises a VariableFrequency Drive (VFD) device which actually comprises a plurality ofindividual Variable Frequency Drives. Each Variable Frequency drive isdedicated to one direct-drive system. Therefore, one Variable FrequencyDrive corresponds to the direct-drive system that drives the fan, andeach of the remaining Variable Frequency Drives is dedicated tocontrolling the direct-drive system of a corresponding variable speedpump. Thus, each direct-drive system is controlled independently.

In an alternate embodiment, variable speed drives (VSD) are used insteadof variable frequency drives.

The variable process control system of the present invention providesadaptive and autonomous variable speed operation of the fan and pumpswith control, supervision and feedback with operator override. Thecomputer system of the variable process control system processes dataincluding cooling tower basin temperature, current process coolingdemand, condenser temperature set-point, tower aerodynamiccharacteristics, time of day, wet-bulb temperature, vibration, processdemand, environmental stress (e.g. windspeed and direction) andhistorical trending of weather conditions to control the variable speedpumps and the variable speed fan in order to control the air and waterflow through the tower and meet thermal demand. These features andoperating characteristics of the variable process control system of thepresent invention enable variation in the L/G ratio of the cooling towerby (A) varying the speed of the fan and pumps simultaneously, or (B)varying the speed of only the fan, or (C) varying the speed of only thepumps. The ability to vary only the speed of the fan allows adjustmentof the air-to-fixed-water ratio for improved operation such as when “hotday” cooling is needed or when icing conditions occur.

One embodiment of the variable process control system of the presentinvention anticipates process demand and increases or decreases the fanspeed in pattern similar to a sine wave over a twenty four (24) hourperiod. The variable process control system accomplishes this by using aRunge-Kutter algorithm (or similar algorithm) that analyzes historicalprocess demand and environmental stress as well as current processdemand and current environmental stress to minimize the energy used tovary the fan speed. This variable process control of the presentinvention is adaptive and learns the process cooling demand byhistorical trending as a function of date and time. The operators of theplant input basin temperature set-point data into the Plant DCS(Distributed Control System). The basin temperature set-point data canbe changed instantaneously to meet additional cooling requirements suchas cracking heavier crude, maintaining vacuum backpressure in a steamturbine or prevent heat exchanger fouling or derate the plant topart-load. In response to the change in the basin temperature set-point,the variable process control system of the present inventionautomatically varies the rotational speed of the direct-drive system,and hence the rotational speed of the fan and pumps.

In an alternate embodiment, a condenser temperature set-point isinputted into the plant Distributed Control System (DCS) by theoperators. The DCS is in electronic signal communication with the dataacquisition (DAQ) device and/or industrial computer of the variableprocess control system of the present invention. The data acquisitiondevice then calculates a collection basin temperature set-point that isrequired in order to meet the condenser temperature set-point. Thevariable process control system then operates the fan and variable speedpumps to maintain a collection basin temperature that meets thecondenser temperature set-point inputted by the operators.

The variable process control system of the present invention utilizesvariable speed direct-drive systems to drive fans and pumps to providethe required cooling to the industrial process even as the environmentalstress changes. Process parameters, including but not limited to,temperatures, pressures and flow rates are measured throughout thesystem in order to monitor, supervise and control cooling of liquids(e.g. water) used by the industrial process. The variable processcontrol system continually monitors cooling performance as a function ofprocess demand and environmental stress to determine available coolingcapacity that can be used for additional process production (e.g.cracking of crude, hot-day turbine output to prevent brown-outs) oridentify cooling tower expansions. The variable process control systemautomatically adjusts cooling capacity when the industrial process is atpart-load conditions (e.g. outage, off-peak, cold day, etc.)

The present invention is applicable to multi-cell cooling towers. In amulti-cell system, the speed of each fan in each cell is varied inaccordance with numerous factors such as Computational Fluid DynamicsAnalysis, thermal modeling, tower configuration, environmentalconditions and process demand.

The core relationships upon which the system and method of the presentinvention are based are as follows:

-   -   A) Mass airflow (ACFM) is directly proportional to fan RPM;    -   B) Fan Static Pressure is directly proportional to the square of        the fan RPM; and    -   C) Fan Horsepower is directly proportional to the cube of the        fan RPM.

The variable process control system of the present invention determinesmass airflow by way of the operation of the direct-drive system. Thevariable process control system of the present invention includes aplurality of pressure devices that are located in the cooling towerplenum. The data signals provided by these pressure devices, along withthe fan speed data from the VFD, fan pitch and the fan map, areprocessed by an industrial computer and used to determine the massairflow in the fan cell.

The variable process control system of the present invention monitorscooling tower performance in real time and compares the performance datato design data in order to formulate a performance trend over time. Ithas been found that trending is the best predictor of performance andtherefore can be used to modify and optimize the fan variable speedschedule, and plan and implement cooling tower service, maintenance andimprovements as a function of process loading, such as hot day or coldday limitations, or selection of the appropriate fill to compensate forpoor water quality. Long term trending is an improvement in trueperformance prediction as opposed to periodic testing which is done inprior art systems.

The present invention is a unique, novel, and reliable approach todetermining cooling tower performance. The variable process controlsystem of the present invention determines the L/G ratio in real timeand adjusts the L/G ratio as a function of environmental stress factors,e.g. weather, temperature, humidity, etc. The determined L/G ratio isstored and used to develop trends which can be used to optimizeoperation of the cooling tower. L/G can be infinitely adjusted withindependent control of pumps and fans. The variable process controlsystem uses fan speed, horsepower and the electrical current draw of thedirect-drive system (i.e. amperes) in conjunction with a measured plenumpressure. The variable process control system also uses this techniquewith the variable speed pumps in order to determine flow rate, clogs andother flow issues. The measured plenum pressure equates to fan inletpressure. The present invention uses key parameters measured by thesystem including measured plenum pressure in combination with the fanspeed, known from the VFD (Variable Frequency Drive), and the design fanmap to determine mass airflow and real time cooling performance. Thissystem of the present invention is then used to recognize poorperformance conditions and alert end-users to perform an inspection andidentify the required corrective action. The plenum pressure is measuredby a pressure device that is located in the fan deck.

The design criteria of the variable process control system of thepresent invention are based upon the thermal design of the tower, theprocess demand, environmental conditions and energy optimization. On theother hand, the prior art variable speed fan gearbox systems are appliedwithout knowledge of the tower thermal capacity and are only controlledby the basin temperature set-point.

A very important feature of the direct-drive system of the presentinvention is that it may be used in new installations (e.g. new towerconstructions or new fan assembly) or it can be used as a “drop-in”replacement. If the direct-drive system is used as a “drop-in”replacement, it will easily interface with all existing fan hubs andprovide the required torque and speed to rotate all existing andpossible fan configurations within the existing “installed” weight andfan height requirements. The direct-drive system of the presentinvention easily interfaces with existing cooling tower structures anddoes not utilize or need auxiliary cooling systems or apparatuses. Thecharacteristics of the high, constant torque of the low variable speeddirect-drive system of the present invention provide the flexibility ofoptimizing fan pitch for a given process demand. The unique combinationof the high torque and low speed characteristics of the motor of thedirect-drive system meets all requirements for driving the cooling towerfan while at the same time, maintaining the height of the existing fanin the fan stack. The weight of the direct-drive system of the presentinvention is less than or equal to the prior art gear box drive systembeing replaced.

The variable process control system of the present invention isprogrammed to operate based on the aforesaid criteria as opposed toprior art systems which are typically reactive to the basin temperature.Airflow generated by the variable process control system of the presentinvention is a function of fan blade pitch, fan efficiency and fan speedand can be optimized for thermal demand (100% cooling) and energyconsumption. Thermal demand is a function of the process. The variableprocess control system of the present invention anticipates coolingdemand based upon historical and actual process parameters, expectedseasonal conditions, historical and environmental conditions, and isdesigned for variable speed, autonomous operation with control andsupervision.

Since the direct-drive system of the present invention delivers constanthigh torque throughout its variable speed range, the fan pitch can beoptimized for expected hot-day conditions (max cooling) and maximumefficiency based on the expected and historical weather patterns andprocess demand of the plant location. With the constant high-torqueproduced by the direct-drive system of the present invention, increasedairflow is achieved with greater fan pitch at slower speeds therebyreducing acoustic signature or fan noise in sensitive areas and alsoprovides greater airflow at 100% fan tip speed.

The variable process control system of the present invention alsoprovides capability for additional airflow or cooling for extremely hotdays and is adaptive to changes in process demand. The variable processcontrol system of the present invention can also provide additionalcooling to compensate for loss of a cooling cell in a multi-cell tower.This mode of operation of the variable process control system isreferred herein to the “Compensation Mode”. In the Compensation Mode,the fan speed of the remaining cells is increased to produce theadditional flow through the tower to compensate for the loss of coolingresulting from the lost cells. The Compensation Mode can also achievethe additional flow through the tower by varying the speed of the fansand the pumps independently. The variable process control system of thepresent invention is programmed not to increase the fan speed greaterthan the fan tip speed when compensating for the loss of coolingresulting from the loss cell. The compensation mode feature is designedand programmed into the variable process control system of the presentinvention based upon the expected loss of a cell and its location in thetower. The variable process control system of the present inventionindependently varies the speed of each fan and the speed of each pump inthe remaining cells in accordance with the configuration, geometry andflow characteristic of the cooling tower and the effect each cell has onthe overall cooling of the cooling tower. This provides the requiredcooling and manages the resultant energy consumption of the coolingtower. The variable process control system of the present inventionmanages the variable speed of the fans and pumps in each cell therebyproviding required cooling while optimizing energy consumption basedupon the unique configuration and geometry of each cooling tower.

Operational characteristics of the variable process control system ofthe present invention include:

-   -   1) autonomous variable speed operation based on process demand,        thermal demand, cooling tower thermal design and environmental        conditions;    -   2) capability to vary the L/G ratio using (A) the combination of        the fan and pumps, or (B) only the fan, or (C) only the pumps;    -   3) adaptive cooling that provides (a) regulated thermal        performance based upon an independent parameter or signal such        as lower basin temperature or condenser water to improve        cracking of heavier crude during a refining process, (b)        regulated temperature control to accommodate steam turbine        back-pressure in a power plant for performance and safety        and (c) regulated cooling to prevent condenser fouling;    -   4) autonomous and independent variable speed operation of fans        in a multi-cell tower;    -   5) fan idle in individual cells of a multi-cell tower based on        thermal demand and unique cooling tower design (i.e. fan idle)        if thermal demand needs have been met;    -   6) real-time feedback which allows monitoring and supervision;    -   7) operator override for stopping or starting the fan, and        controlling basin temperature set-point for part-load operation;    -   8) uses fan speed, electrical current draw of the direct-drive        system, the horse power of the direct-drive system, and plenum        pressure in combination with environmental conditions such as        wind speed and direction, temperature and wet-bulb temperature        to measure and monitor fan airflow and record all operating        data, process demand trend and environmental conditions to        provide historical analysis for performance, maintenance        actions, process improvements and expansions;    -   9) vibration control which provides 100% monitoring, control and        supervision of the system vibration signature with improved        signature fidelity that allows system troubleshooting, proactive        maintenance and safer operation (post processing);    -   10) vibration control that provides 100% monitoring, control and        supervision for measuring and identifying system resonances in        real time within the variable speed range and then locking them        out of the operating range;    -   11) vibration control that provides 100% monitoring, control and        supervision for providing post processing of vibration        signatures using an industrial computer and algorithms such as        Fast Fourier Transforms (FFT) to analyze system health and        provide system alerts to end users such as fan imbalance as well        control signals to the DAQ (data acquisition) device in the case        of operating issues such as impending failure;    -   12) provides for safe Lock-Out, Tag-Out (LOTO) of the fan drive        system by controlling the deceleration of the fan and holding        the fan at stop while a fan lock is engaged with the drive        system and all forms of energy are removed from the cell        including cooling water to the cell so as to prevent an updraft        that could cause the fan to windmill in either direction;    -   13) provides for a proactive maintenance program based on actual        operating data, cooling performance, trending analysis and post        processing of data using a Fast Fourier Transform to identify        issues such as fan imbalance, impending fan hub failure,        impending fan blade failure and fan failure and provide service,        maintenance and repair and replacement before a failure leads to        a catastrophic event and loss of life, and the loss of the        cooling asset and production.    -   14) provides a predictive maintenance program based on actual        operating data, cooling performance, trending analysis and        environmental condition trending in order to provide planning        for cooling tower maintenance on major cooling tower subsystems        such as fill replacement and identify cooling improvements for        budget creation and planning for upcoming outages;    -   15) monitoring capabilities that alert operators if the system        is functioning properly or requires maintenance or an        inspection;    -   16) operator may manually override the variable control system        to turn fan on or off;    -   17) provides an operator with the ability to adjust and fine        tune cooling based on process demand with maximum hot-day        override;    -   18) monitors auxiliary systems, such as pumps, to prevent        excessive amounts of water from being pumped into the tower        distribution system which could cause collapse of the cooling        tower;    -   19) continuously measures current process demand and        environmental stress;    -   20) varies the fan speed in gradual steps as the variable        process control system learns from past process cooling demand        as a function of season, time, date and environmental conditions        to predict future process demand, wherein the variation of fan        speed in gradual steps minimizes energy draw and system wear;    -   21)since the direct-drive system of the present invention is not        limited in reverse operation, regenerative drive options may be        used to provide power to the grid when fans are windmilling in        reverse;    -   22) automatic deicing; and    -   23) reverse operation, wherein the epicyclic traction drive        system has the same operational characteristics as in forward        operation.

The direct-drive system and variable process control system of thepresent invention are applicable to wet-cooling tower systems,air-cooled heat exchangers (ACHE), HVAC, mechanical towers and chillers,and blowers regardless of mounting configuration and orientation.

In one aspect, the present invention is directed to a wet-cooling towersystem comprising a direct-drive system for driving the fan and anintegrated variable process control system. The wet-cooling tower systemcomprises a wet-cooling tower that comprises a tower structure that hasfill material located within the tower structure, a fan deck locatedabove the fill material, and a collection basin located beneath the fillmaterial for collecting cooled liquid. A fan stack is positioned uponthe fan deck and a fan is located within the fan stack. The fancomprises a hub to which are connected a plurality of fan blades. Thedirect-drive system comprises a high-torque, low variable speed, loadbearing epicyclic traction drive system that has a rotatable shaftconnected to the fan hub. The high-torque, low variable speed, loadbearing epicyclic traction drive system comprises a bearing system andstructure that supports the loads of large diameter fans, e.g.rotational loads, axial thrust loads, axial reverse thrust loads, fandead weight, radial loads, moment loads, and yaw loads. The high-torque,low variable speed, load bearing epicyclic traction drive systemprovides torque multiplication and speed reduction combined with anyelectric motor. The high-torque, low variable speed, load bearingepicyclic traction drive system can be mounted in any position such thatthe output shaft of the epicyclic traction drive system can be orientedin any position, e.g. upward, downward, horizontal, angulated, etc. Thiscan be achieved because the epicyclic traction drive system is a sealedsystem and eliminates the oil bath system which is used in prior artsystems.

In one embodiment, the epicyclic traction drive system has a rotationalspeed between about 0.00 RPM and 500 RPM, and horsepower between 1.0 HPand 500 HP. In another embodiment, the epicyclic traction drive systemis configured to have rotational speeds that exceed 500 RPM. Theepicyclic traction drive system may be configured to provide otherrotational speeds. The epicyclic traction drive system interfaces withall fans having diameters between about one foot and forty feet. Theoutput shaft of the epicyclic traction drive system can be directlyconnected to the fan, or directly connected to the fan hub, or connectedto the fan with a shaft adapter, or connected to the fan hub with ashaft adapter, or connected to the fan with a shaft extension.

In an alternate embodiment, the epicyclic traction drive system is usedto drive fans that are supported by a separate, independent structure.Specifically, in such an embodiment, the axial, yaw and most radialloads are supported by the separate, independent structure and theepicyclic traction drive system provides torque, speed and some radialloading.

The epicyclic traction drive system is sealed to prevent contaminationor damage by environmental conditions and complies with Class One,Division One Hazardous Area Classification.

In comparison to the prior art, the vibration signature of the epicyclictraction drive system has a low amplitude with clear signature fidelitywhich allows for 100% monitoring and supervision providing for proactiveservice and maintenance and an improvement in safety and production. Thetrending of past cooling tower operation and post processing inconjunction with vibration signal analysis (FFT) determines whetherother vibration signatures are indicating such issues as a fan bladeimbalance, fan blade pitch adjustment, lubrication issues, bearingissues and impending fan hub, fan blade and motor bearing failure, whichare major safety issues. The location of the vibration sensors at themotor bearings also allows for programming of lower amplitude shut-offparameters.

As described in the foregoing description, the variable process controlsystem of the present invention comprises one or more sensors that mayinclude accelerometers, velocity and displacement transducers or similardevices to monitor, supervise and control the vibration characteristicsof the direct-drive system and the direct-drive pump system that pumpswater to and from the cooling tower. One or more vibration sensors arelocated in the casing of the epicyclic traction drive system and mountedor positioned on a corresponding bearing or structure. In such aconfiguration, the vibration sensors are protected from the environment.

As a result of the structure and design of the epicyclic traction drivesystem and the direct connection of the epicyclic traction drivesystem's output shaft to the fan hub, operation is very smooth with lowvibration.

The present invention has significantly less “frequency noise” becausethe present invention eliminates ladder frames, torque tubes, shafts,couplings, gearboxes and gearmesh that are commonly used in prior artsystems. In accordance with the invention, vibration sensors are locatedat the bearings of the motor of the direct-drive system. Each vibrationsensor outputs signals representing vibrations of the motor bearings.Thus, vibrations are read directly at the bearings that are directlycoupled to the fan as opposed to the prior art technique of measuringthe vibrations at the ladder frame. As a result of this importantfeature of the invention, the present invention can identify, analyzeand correct for changes in the performance of the fan, thereby providinga longer running system that is relatively safer. In an alternateembodiment, additional vibration sensors are utilized in variouslocations on the direct drive system. In another embodiment, vibrationsensors are also positioned at various locations in the cooling towerstructure.

The variable process control system of the present invention furthercomprises a plurality of temperature sensors in electrical signalcommunication with the data collection device. Temperature sensorsmeasure the temperature of the exterior of the casing or housing of thedirect-drive system. Temperature sensors also measure the temperature onthe exterior of the motor housing. Temperature sensors are also locatedwithin the casing of the direct-drive system to measure the temperaturewithin the casing. Temperature sensors are located in the basin tomeasure temperature of liquid (e.g. water) within the basin. Temperaturesensors also measure the environmental temperature (e.g. ambienttemperature). Another temperature sensor measures the temperature of theair in the fan stack before the fan. The variable process control systemof the present invention further includes at least one pressure sensorlocated in the fan deck that measures the pressure in the fan plenum,which equates to the pressure at the fan inlet. The variable processcontrol system further comprises a computer in data signal communicationwith the data collection device. The computer comprises a memory and asignal processor to process the motor status signals, the pump flow ratesignals and the signals outputted by the vibration sensors and heatand/or temperature sensors. The computer outputs control signals to thedata collection device for routing to the variable frequency drivedevice in order to control the speed of the motor in response to theprocessing of the sensor signals, pump flow rate signals and motorstatus signals.

The variable process control system of the present invention comprises aplurality of vibration sensors which may include accelerometers,velocity and displacement transducers or similar devices to monitor,supervise and control vibration characterisitics of the direct-drive fanand variable speed pump system. The aforesaid vibration sensors detectvarious regions of the frequency bands of the motor, fan and coolingtower that are to be monitored and analyzed. Thus, the sensors monitorthe frequency of vibrations of the tower so as to allow determination ofthe resonance frequency or frequencies of the tower. The variableprocess control system also includes a fugitive gas emission probelocated on the motor as a Line Replaceable Unit (LRU) for detectingleakage of gasses from heat exchangers and other equipment.

Some key features of the system of the present invention are:

1) reverse, de-ice, flying-start and soft-stop modes of operation withinfinite control of fan speed in both reverse and forward directions;

2) variable process control which can be applied to any one of a varietyof industries, including cooling towers, HVAC systems, blowers,refineries, power generation, chemical processes and pulp and paperplants;

3) capability to adjust the L/G ratio so as to provide 100% loadoperation or part-load operation in various wind and weather conditions;

4) maintaining vacuum backpressure for a steam turbine;

5) prevents damage and fouling of heat exchangers, condensers andauxiliary equipment;

6) simplified installation using only four bolts and area classifiedquick disconnect communication cable and factory terminated power cableallow for “plug and play” installation;

7) line-replaceable units such as sensors, meters, probes, hazardous gasmonitors, or similar devices are integrated into the motor casing (orhousing) to detect and monitor fugitive gas emissions in the fanair-steam accordance with the U.S. EPA (Environmental Protection Agency)regulations;8) variable speed operation with low, variable speed capability;9) cells in multi-cell tower can be operated independently to meetcooling and optimize energy;10) 100% monitoring, autonomous control and supervision of the system;11) automated and autonomous operation;12) relatively low vibrations and high vibration fidelity due to systemarchitecture and structure;13) changes in vibration signals are detected and analyzed usingtrending data and post processing such as Fast Fourier Transform (FFT)or other similar programs;14) vibration sensors are integrated into the motor and thus protectedfrom the surrounding harsh, humid environment;15) uses a variable frequency drive (VFD) device that provides signalsrepresenting motor torque and speed;16) uses a DAQ (data acquisition) device that collects signals outputtedby the VFD and other data signals;17) uses a processor that processes signals collected by the DAQ device,generates control signals, routes control signals back to VFD andimplements algorithms (e.g. FFT) to process vibration signals;18) uses a mechanical fan-lock that is applied directly to the shaft ofthe motor to prevent rotation of the fan when power is removed formaintenance and hurricane service;19) uses a Lock-Out-Tag-Out (LOTO) procedure wherein the fan isdecelerated to 0.0 RPM under power and control of the motor and VFD andthe motor holds the fan at 0.0 RPM while a mechanical lock device isapplied to the motor shaft to prevent rotation of the fan, and then allforms of energy are removed per OSHA Requirements for Service,Maintenance and Hurricane Duty (e.g. hurricane, tornado, shut-down,etc.);20) produces regenerative power when the fan is windmilling;21) the motor and VFD provide infinite control of the fan accelerationand can hold the fan at 0.0 RPM, and also provide fan deceleration andfan rotational direction;22) allows fan to windmill in reverse due to cooling water updraft;23) the direct-drive system can operate in all systems, e.g. wet-coolingtowers, ACHEs, HVAC systems, chillers, blowers, etc.;24) the direct-drive system directly drives the fan;25) the direct-drive systems directly drive the pumps; and26) the direct-drive system can be connected to a fan hub of a fan, ordirectly connected to a one-piece fan.

BRIEF DESCRIPTION OF THE DRAWINGS

Although the scope of the present invention is much broader than anyparticular embodiment, a detailed description of the preferredembodiments follows together with illustrative figures, wherein likereference numerals refer to like components, and wherein:

FIG. 1 is a side view, in elevation, of a wet-cooling tower that uses aprior art fan drive system;

FIG. 2A is a block diagram of a direct-drive system for a fan of acooling system in accordance with one embodiment of the presentinvention;

FIG. 2B is a block diagram of a direct-drive system for a fan of coolingsystem in accordance with another embodiment of the present invention;

FIG. 2C is a block diagram of a direct-drive system for a fan of coolingsystem in accordance with a further embodiment of the present invention;

FIG. 2D is a block diagram of a direct-drive system for a fan of coolingsystem in accordance with another embodiment of the present invention;

FIG. 2E is a block diagram of a direct-drive system for fan of a coolingsystem in accordance with another embodiment of the present invention;

FIG. 2F is a block diagram of a direct-drive system for a fan of coolingsystem in accordance with another embodiment of the present invention;

FIG. 2G is a block diagram of a direct-drive system for a fan of acooling system in accordance with another embodiment of the presentinvention;

FIG. 2H is a block diagram of a direct-drive system for a fan of acooling system in accordance with another embodiment of the presentinvention;

FIG. 2I is a block diagram of a direct-drive system for a fan of acooling system in accordance with another embodiment of the presentinvention;

FIG. 2J is another diagram of the direct-drive system shown in FIG. 2B;

FIG. 2K is a cross-sectional view taken along line 2K-2K in FIG. 2J;

FIG. 2L is a block diagram of a variable process control system inaccordance with one embodiment of the present invention, wherein thevariable process control system controls the operation of a coolingtower;

FIG. 2M is a side view, partially in cross-section, of a load bearing,direct drive system in accordance with another embodiment of the presentinvention;

FIG. 2N is a side view of a load bearing, direct drive system inaccordance with a further embodiment of the present invention;

FIG. 2O is a side view of a load bearing, direct drive system inaccordance with yet another embodiment of the present invention;

FIG. 2P is a side view, partially in cross-section, of a load bearing,direct drive system in accordance with yet a further embodiment of thepresent invention;

FIG. 3 is a diagram of the feedback loops of the variable processcontrol system shown in FIG. 2L;

FIG. 4 is a block diagram illustrating the interconnection of particularsubsystem components shown in FIG. 2L;

FIG. 5A is a diagram showing the internal configuration of a variablespeed, load bearing permanent magnet motor shown in FIG. 4, the diagramspecifically showing the location of the bearings of the permanentmagnet motor;

FIG. 5B is a diagram showing a portion of the variable speed, loadbearing permanent magnet motor of FIG. 5A, the diagram showing thelocation of the accelerometers within the motor housing;

FIG. 6 is a plot of motor speed versus horsepower for the variablespeed, load bearing permanent magnet motor shown in FIG. 5A and used indirect-drive fan system of the present invention;

FIG. 7 is a graph illustrating a comparison in performance between thedirect-drive fan system of the present invention and a prior artgearbox-type fan drive system that uses a variable speed inductionmotor;

FIG. 8 is a side view, in elevation and partially in cross-section, of awet-cooling tower employing the direct-drive fan system of the presentinvention;

FIG. 9 is a graph showing a fan speed curve that is similar to a sinewave and represents the increase and decrease in the fan speed over atwenty-four hour period in accordance with an Energy Optimization Modeof the present invention, the bottom portion of the graph showing a fanspeed curve representing changes in fan speed for a prior art variablespeed fan drive system;

FIG. 10A is a side view, in elevation and partially in cross-section, ofan induced draft ACHE that utilizes a partial load bearing, direct-drivefan system of the present invention;

FIG. 10B is a side view, in elevation and partially in cross-section, ofa forced draft ACHE that utilizes the direct-drive fan system of thepresent invention;

FIG. 11 is a side view, in elevation and partially in cross-section, ofanother induced draft ACHE that utilizes the direct-drive fan system ofthe present invention;

FIG. 12A is a side view, partially in cross-section, of the direct-drivesystem of the present invention installed in a wet cooling tower;

FIG. 12B is a bottom view of the direct-drive system depicted in FIG.12A, the view showing the mounting holes in the housing of thedirect-drive system;

FIG. 13 shows an enlargement of the view of FIG. 12A, the view beingpartially in cross-section;

FIG. 14 is a side view, in elevation, showing the interconnection of thedirect-drive system shown in FIGS. 2A, 12A and 13 with a fan hub;

FIG. 15A is a diagram of a multi-cell cooling system, wherein each cellutilizes the direct-drive system of the present invention;

FIG. 15B is a top view of the multi-cell cooling system shown in FIG.15A;

FIG. 15C is a block diagram of a motor-control center (MCC) that isshown in FIG. 15A;

FIG. 16A is a flowchart of a lock-out-tag-out (LOTO) procedure used tostop the fan in order to conduct maintenance procedures;

FIG. 16B is a flow chart a Flying-Start mode of operation that can beimplemented by the direct-drive system and variable process controlsystem of the present invention;

FIG. 16C is a graph of speed versus time for the Flying-Start mode ofoperation’

FIG. 17 is a graph of an example of condenser performance as a functionof water flow rate;

FIG. 18 is a partial view of the permanent magnet motor shown in FIGS. 4and 5A, the permanent magnet motor having mounted thereto aline-replaceable vibration sensor unit in accordance with anotherembodiment of the invention;

FIG. 19 is a partial view of the permanent magnet motor shown in FIGS. 4and 5A, the permanent magnet motor having mounted thereto a linereplaceable vibration sensor unit in accordance with a furtherembodiment of the invention;

FIG. 20 is partial view of the permanent magnet motor shown in FIGS. 4and 5A having mounted thereto a line replaceable vibration sensor unitin accordance with a further embodiment of the invention;

FIG. 21A is a top, diagrammatical view showing a fan-lock mechanism inaccordance with one embodiment of the invention, the fan lock mechanismbeing used on the rotatable shaft of the motor shown in FIGS. 4 and 5A,the view showing the fan lock mechanism disengaged from the rotatablemotor shaft in order to allow rotation of the motor shaft;

FIG. 21B is a top, diagrammatical view showing the fan lock mechanism ofFIG. 21A, the view showing the fan lock mechanism engaged with therotatable motor shaft in order to prevent rotation of the motor shaft;

FIG. 21C is a side elevational view of the motor shown in FIGS. 4 and5A, the view showing the interior of the motor and the fan-lockmechanism shown in FIGS. 21A and 21B mounted on the motor about theupper portion of the motor shaft, the view also showing an additionalfan-lock mechanism shown in FIGS. 21A and 21B mounted to the motor aboutthe lower portion of the motor shaft;

FIG. 22 is a side elevational view of the upper portion of the permanentmagnet motor of FIGS. 4 and 5A, the permanent magnet motor havingmounted thereto a caliper-type lock mechanism for engaging the upperportion of the shaft of the motor;

FIG. 23 is a side elevational view of the lower portion of the permanentmagnet motor of FIGS. 4 and 5A, the permanent magnet motor havingmounted thereto a caliper-type lock mechanism for engaging the lowerportion of the shaft of the motor;

FIG. 24 is a side elevational view of the lower portion of the permanentmagnet motor of FIGS. 4 and 5A, the permanent magnet motor havingmounted thereto a band-lock mechanism for engaging the lower portion ofthe shaft of the motor;

FIG. 25 is a side elevational view of the upper portion of the permanentmagnet motor of FIGS. 4 and 5A, the permanent magnet motor havingmounted thereto a band-lock mechanism for engaging the upper portion ofthe shaft of the motor;

FIG. 26 is a block diagram showing the direct-drive system and variableprocess control system of the present invention used with a wet-coolingtower that is part of an industrial process;

FIG. 27 is a diagrammatical view of the direct-drive fan system of thepresent invention used in a HVAC system, the view showing thedirect-drive system driving an axial condenser fan;

FIG. 28 is a top view of an axial condenser fan shown in FIG. 27;

FIG. 29 is a side view, partially in cross-section, showing thedirect-drive system of the present invention used in a HVAC system, theview showing the direct-drive system driving a centrifugal fan;

FIG. 30 is a side view of a centrifugal fan apparatus that utilizes thedirect-drive system of the present invention;

FIG. 31 is a view of the interior of the centrifugal fan apparatus ofFIG. 30 wherein the direct-drive system is mounted to the interiorportions of the housing of the centrifugal fan apparatus; and

FIG. 32 is an alternate embodiment of the centrifugal fan apparatusshown in FIGS. 31 and 31.

BEST MODE FOR CARRYING OUT THE INVENTION

As used herein, the term “L/G ratio” shall mean the air-to-water ratiothat governs the performance of a wet cooling tower relative to thelatent heat of evaporation.

As used herein, the terms “process”, “plant process” or “industrialprocess” shall mean an industrial process such as a petroleum refinery,power plant, turbine, crude cracker, fertilizer plant, glassmanufacturing plant, chemical plant, etc.

As used herein, the terms “process liquid” means the liquids, such aswater or other coolant, that are used for cooling purposes in theprocess.

As used herein, the terms “process demand” or “process cooling demand”mean the amount of cooling liquids required by the process.

As used herein, the term “part-plant load” means process demand that isless than maximum process demand.

As used herein, the terms “basin temperature” or “collection basintemperature” mean the temperature of the water or other liquid that isin the collection basin of a wet-cooling tower;

As used herein, the term “Environmental Stress” shall mean,collectively, ambient temperature, relative humidity, dry-bulbtemperature, wet-bulb temperature, wind speed, wind direction, solargain and barometric pressure.

As used herein, the term “Cooling Tower Thermal Capacity” is theheat-rejection capability of the cooling tower. It is the amount of coldwater that can be returned to the process for given temperature and flowrate at maximum hot-day and wet-bulb conditions. Cooling Tower ThermalCapacity will be reduced as the cooling tower components degrade, suchas the fill material becoming clogged due to poor water quality. For agiven ΔT (difference between temperatures of hot and cold water) andflow rate, the cooling tower fans will have to operate at higher speedand for longer amounts of time given the environmental stress in adegraded tower.

As used herein, the term “process thermal demand” or “thermal demand”means the heat that has to be removed from the process liquid (e.g.water) by the cooling tower. In its simplest terms, thermal demand ofthe process is expressed as the water temperature from the process (hotwater) and water temperature returned to the process (cold water) for agiven flow rate;

As used herein, the terms “fan map” and “fan performance curve”represent the data provided for fan blades with a given solidity.Specifically, the data represents the airflow of air moved by a specificfan diameter, model and solidity for a given fan speed and pitch at agiven temperature and wet-bulb (air density).

As used herein, the terms “trending” or “trend” means the collection ofcooling tower parameters, events and calculated values with respect totime that define cooling tower operating characteristics such as coolingperformance as a function of environmental stress and Process ThermalDemand.

As used herein, the term “motor” shall mean any electric motor with arotor and stator that creates flux.

Referring to FIG. 2A, there is shown a general block diagram of adirect-drive system for a fan in a cooling system in accordance with oneembodiment of the invention. Direct-drive system 2000 generallycomprises torque multiplier device 2002 and motor 2004. Motor 2004includes a housing (or casing) and rotatable shaft 2006 (shown inphantom) that drives torque multiplier device 2002. Direct-drive system2000 includes electrical connector 2008 which is connected to the motorhousing and is configured to receive electrical power and, depending onthe particular embodiment, control signals that control motor 2004and/or torque multiplier device 2002. Torque multiplier device 2002includes rotatable output shaft 2010 that is connected to a fan of acooling system. The interconnection of rotatable output shaft 2010 andthe fan is discussed in greater detail in the ensuing description.

It is to be understood that the ensuing description describes numerousembodiments of the direct-drive system of the present invention. Forexample, in certain embodiments, motor 2004 is a single speed motorwithout any associated electronic control devices, and in otherembodiments, motor 2004 is a variable speed motor having either externalor integrated electronic control. Similarly, in certain embodiments,torque multiplier device 2002 is a fixed or constant ratio device, andin other embodiments, it is variable speed device that may have externalor integrated control electronics. In another embodiment, motor 2004 isa single speed permanent magnet motor without any associated electroniccontrol devices.

In a preferred embodiment, the direct-drive system of the presentinvention is designed and constructed so as to provide infinitevariation in torque and speed with load. This allows a relativelysmaller sized motor to be used and also provides reverse direction andcontrolled start and stop without a clutch. Specifically, in theembodiment shown in FIG. 2A, direct-drive system 2000 is constructedsuch that torque multiplier device 2002 is a sealed system and designedand constructed to bear the loads of a cooling tower fan. Torquemultiplier device 2002 is connected and sealed to motor 2004. Motor 2004is a load-bearing motor that can bear the loads of a cooling tower fanwhether the fan is rotating or at 0.0 rpm. Motor 2004 is designed sothat it can be vented as required. Thus, the casing, bearing and shaftdesign of direct-drive system 2000 ensures structural and dynamicintegrity and also allows for cooling of motor 2004 without the use of ashroud or similar device which is typically used in prior art fan drivesystems. For example, a typical prior art shroud is described in U.S.Pat. No. 7,880,348. Since direct-drive system 2000 is a sealed device,it requires minimum maintenance. Shaft alignments and oil changes arenot needed. Since there is no drive shaft, there will be no couplingfailures. All bearings in torque multiplier device 2002 and motor 2004are protected from contamination thereby extending the operational lifeof the bearings. In a preferred embodiment, direct-drive system 2000, aswell as all direct-drive system embodiments of the present invention,meet or exceed the requirements of Class 1, Div. 2, Groups B, C and D.In one embodiment, reverse direction of the direct-drive system isachieved by manually reversing electrical leads. In another embodiment,a switch is installed to enable reverse direction.

All embodiments of the direct-drive system of the present invention aredesigned and configured to directly drive fans in all types of systemsthat utilize fans, e.g. wet cooling towers, air-cooled heat exchangers(ACHE), chillers, blowers and HVAC (heating ventilation air condition)systems. Wet cooling towers or air-cooled heat exchangers (ACHE) arecommonly used to cool fluids used in an industrial process, e.g.petroleum refining. An example of a wet cooling tower is described inU.S. Pat. No. 8,111,028, entitled “Integrated Fan Drive System ForCooling Tower”, issued Feb. 7, 2012, the disclosure of which patent ishereby incorporated by reference. Examples of air-cooled heat exchangers(ACHE) are described in U.S. Pat. No. 8,188,698, entitled “IntegratedFan-Drive System For Air-Cooled Heat-Exchanger (ACHE)”, issued May 29,2012, the disclosure of which patent is hereby incorporated byreference. The particular fans utilized in HVAC systems are discussed indetail in the ensuing description. In order to facilitate understandingof the invention and its operation, a brief description is now presentedwhich shows direct-drive 2000 connected to a fan of a wet-cooling tower.

Referring to FIGS. 13 and 14, there is shown fan 12 that is utilized ina wet-cooling tower. Fan 12 comprises fan hub 16 and fan blades 18 thatare connected to fan hub 16. Fan hub 16 has a tapered bore 2100 withintapered coupling 2102. In a preferred embodiment, tapered coupling 2102is a Browning Morse, or equivalent, tapered coupling. Fan hub 16 has topfan hub disk 2104 and bottom fan hub disk 2106. Fan 12 includes fan sealdisk 2108 that is connected to top fan hub disk 2104 by connectingmembers 2105. Tapered coupling 2102 is located between top fan hub disk2104 and bottom fan hub disk 2106. Rotatable output shaft 2010 of torquemultiplier device 2002 is configured as a keyed, output shaft thatinterfaces with complementary shaped, tapered coupling 2102.Specifically, output shaft 2010 of torque multiplier device 2002 isconfigured to have channel 2110 that is shaped to receive acomplementary key structure that is within the circular walls of taperedcoupling 2102. Tapered bushing 2112 and set screw 2114 are used to lockfan 12 to shaft 2010. Specifically, set screw 2114 fastens taperedbushing 2112 to output shaft 2010 to prevent movement of tapered bushing2112.

It is to be understood that drive-drive system 2000, as well as theother direct-drive system embodiments described herein, may be used withother models or types of fans. For example, direct-drive system 2000 maybe used with any of the commercially available 4000 Series Tuft-LiteFans manufactured by Hudson Products, Corporation of Houston, Tex. Inanother example, direct-drive system 2000 is connected to a fan that isconfigured without a hub structure. Such fans are known arewhisper-quiet fans or single-piece wide chord fans. When single-piecewide chord fans are used, rotatable output shaft 2010 of torquemultiplier device 2002 is directly bolted or connected to the fan. Onecommercially available whisper-quiet fan is the PT2 Cooling TowerWhisper Quiet Fan manufactured by Baltimore Aircoil Company of Jessup,Md.

As shown in FIG. 13, fan 12 operates within fan stack 14. Fan stack 14is supported by fan deck 250. Fan stack 14 has a generally parabolicshape that seals the fan at the narrow region to provide proper fanhead. Fan stack 14 widens in diameter at the top of stack 14 forimproved recovery and performance. In other embodiments, fan stack 14can have a straight cylinder shape (i.e. cylindrical shape). Wet coolingtowers typically utilize fill material, not shown but which is describedin the aforementioned U.S. Pat. No. 8,111,028.

In accordance with the invention, the direct-drive system of the presentinvention may be configured with any one of a variety of combinations ofmotors and torque multiplier devices. For example, motor 2004 may beconfigured as any of a variety of suitable motors including:

-   -   a) single speed Totally Enclosed Fan Cooled (TEFC) AC induction        motor (e.g. asynchronous motor);    -   b) variable speed TEFC AC induction motor;    -   c) inverted rated induction motor with VFD;    -   d) switched reluctance motor;    -   e) brushless DC motor;    -   f) pancake DC motor;    -   g) synchronous AC motor;    -   h) salient pole interior permanent magnet motor;    -   i) interior permanent magnet motor;    -   j) finned laminated, permanent magnet motor;    -   k) series-wound motor or universal motor;    -   l) traction motor;    -   m) series-wound field, brushed DC motor;    -   n) stepper motor; and    -   o) stacked lamination frame motor.        Other types of suitable AC and DC motors include sinewave        motors, hysteresis motors, step motors, reluctance motors,        switched reluctance motors, synchronous reluctance motors,        variable reluctance motors, hybrid motors, polyphase motors,        single phase motors, wound rotor motors, squirrel cage motors,        capacitor motors, shaded pole motors, DC permanent magnet        commutator motors, homopolar motors, wound field motors, wound        field shunt motors, and compound wound field motors.

It is to be understood that the direct-drive system of the presentinvention may be used with any electric motor having a rotor and statorthat creates flux.

In one embodiment, motor 2004 is the permanent magnet motor described inthe aforementioned U.S. Pat. Nos. 8,111,028 and 8,188,698.

In another embodiment, motor 2004 is the motor described in U.S. PatentApplication Publication No. US2006/0284511, entitled “EnhancedElectrical Machine Cooling”, published Dec. 21, 2006, the disclosure ofwhich published application is hereby incorporated by reference.

In another embodiment, motor 2004 is synchronous reluctance motor.Examples of synchronous reluctance motors are disclosed in U.S. PatentApplication Publication Nos. 2012/0212215 and 2012/0086289, thedisclosures of which published patent applications are herebyincorporated by reference. Another example of a suitable synchronousreluctance motor is the ABB IE4 synchronous reluctance motor designedand/or manufactured by ABB Discrete Automation and Motion, Motors &Generators of Sweden and ABB Corporate Research of Sweden.

In another embodiment, motor 2004 is the motor described in UnitedKingdom Patent No. GB 2462940 entitled “Electric Motor and ElectricGenerator”, issued Jul. 28, 2010, the disclosure of which patent ishereby incorporated by reference. The motor described in United KingdomPatent No. GB 2462940 is a stepper motor and has a built-in inverterwhich eliminates the need for an external variable frequency drive(VFD).

In another embodiment, motor 2004 is the fault tolerant brushless DCmotor described in published European Patent Application No. EP 0673559entitled “Motor System With Individually Controlled Redundant Windings”,the disclosure of published application is hereby incorporated byreference.

FIGS. 4 and 5A show one embodiment of motor 2004 that may be used in thedirect-drive system of the present invention. In this embodiment, motor2004 is a high torque, low variable speed, permanent magnet motor. Thispermanent magnet motor has a relatively high flux density and iscontrolled only by electrical signals provided by VFD device 22. Thepermanent magnet motor includes stator 32 and rotor 34. Referring toFIG. 5A, in accordance with one embodiment of the invention, theclearance between stator 32 and rotor 34 is 0.060 inch and is designatedby the letter “X” in FIG. 5A. The permanent magnet motor furthercomprises spherical roller thrust bearing 40 which is located at thelower end of motor shaft 2006. Spherical roller thrust bearing 40absorbs the thrust load caused by the weight of fan 12 and fan thrustforces due to airflow. The permanent magnet motor also includescylindrical roller bearing 42 which is located immediately abovespherical roller thrust bearing 40. Cylindrical roller bearing 42opposes radial loads at the thrust end of shaft 2006. Radial loads arecaused by fan assembly unbalance and yaw moments due to unsteady windloads. The permanent magnet motor further comprises tapered rolleroutput bearing 44. Tapered roller output bearing 44 is configured tohave a high radial load capability coupled with thrust capability tooppose the relatively low reverse thrust loads that occur duringde-icing (reverse rotation) or high wind gust. Although three bearingsare described, the permanent magnet motor is actually a two-bearingsystem. The “two bearings” are cylindrical roller bearing 42 and taperedroller output bearing 44 because these two bearings are radial bearingsthat locate and support the motor shaft relative to the motor casing orhousing 21 and the mounting structure. Spherical roller thrust bearing40 is a thrust bearing that is specifically designed so that it does notprovide any radial locating forces but only axial location. Theparticular design, structure and location of the bearings and theparticular design and structure of the motor casing 21, rotor 34 andshaft 2006 cooperate to maintain the clearance “X” of 0.060 inch betweenstator 32 and rotor 34. It is necessary to maintain this clearance “X”of 0.060 inch in order to produce the required electrical flux densityand obtain optimal motor operation. Thus, in accordance with theinvention, the bearings of the motor bear the loads of a rotating fanwhile simultaneously maintaining the clearance “X” of 0.060 inch betweenstator 32 and rotor 34. This feature is unique to motor design and isreferred to herein as a “load bearing motor”. The design of thepermanent magnet motor 2004 has a reduced Life-Cycle Cost (LCC) ascompared to the prior art gearbox fan drive systems described in theforegoing description. Bearing housing 50 houses bearing 44. Bearinghousing 52 houses bearings 40 and 42. Bearing housings 50 and 52 areisolated from the interior of motor housing 21 by nitrile rubber, doublelip-style radial seals. The combination of the low surface speed ofmotor shaft 2006 and synthetic lubricants result in accurate predictedseal reliability and operational life. The permanent magnet motorincludes seal housing 53 that comprises a Grounded Inpro™ Seal bearingisolator. This Grounded Inpro Seal™ bearing isolator electricallygrounds the bearings from the VFD. The motor shaft seal comprises anInpro™ seal bearing isolator in tandem with a double radial lip seal.The Inpro™ seal bearing isolator is mounted immediately outboard of thedouble radial lip seal. The function of the Inpro™ seal is to seal thearea where shaft 2006 penetrates top cover 21A of motor housing 21. TheInpro seal also incorporates a fiber grounding brush to preventimpressed currents in shaft 2006 that could damage the bearings. Thedouble radial lip seal excludes moisture and solid contaminants from theseal lip contact. Motor housing 21 includes bottom cover 21B. In oneembodiment, the permanent magnet motor has the following operational andperformance characteristics:

-   -   Speed Range: 0-250 RPM    -   Maximum Power: 133 hp/100 KW    -   Number of Poles: 16    -   Motor Service Factor: 1:1    -   Rated Current: 62 A (rms)    -   Peak Current: 95 A    -   Rated Voltage: 600 V    -   Drive Inputs: 460 V, 3 phase, 60 Hz, 95 A (rms max. continuous)    -   Area Classification: Class 1, Division 2, Groups B, C, D    -   Insulation Class H

Motor 2004 also includes O-rings between housing 21 and housing covers21A and 21B to provide a minimum IP65 Protection which is required forcooling tower applications. In one embodiment, the bearings of motor2004 are sealed so as to eliminate maintenance and lubrication.

Due to the fan hub interface, the output shaft of the drive-system ofthe present invention is relatively large resulting in the relativelylarge bearing design of motor 2004. Combined with the required slowspeed for rotating the fan, the bearing system is only 20% loaded,thereby providing an L10 life of 875,000 hours. The 20% loading andunique bearing design of motor 2004 provides high fidelity of vibrationsignatures and consistent narrow vibration band signatures well belowthe current trip setting values. As a result, there is improvedmonitoring via historical trending and improved health monitoring viavibration signatures beyond the operating tolerance. Motor 2004 iscapable of rotating fans of different diameters at all speeds andtorques in both directions and is specifically designed to bear radialand yaw loads from the fan, axial loads in both directions from fanthrust and fan dead weight, and reverse loads which depend upon themounting orientation of motor 2004, e.g. shaft up, shaft down, shaft inhorizontal orientation, or combination thereof.

The permanent magnet motor shown in FIGS. 4 and 5A can be configured tohave different operational characteristics. However, it is to beunderstood that in all embodiments, the permanent magnet motor isdesigned to the requirements of Class 1, Div. 2, Groups B, C and D. FIG.6 shows a plot of speed vs. horsepower for the permanent magnet motorshown in FIGS. 4 and 5A. However, it is to be understood that theaforesaid operational and performance characteristics just pertain toone embodiment of the permanent magnet motor and that this permanentmagnet motor may be modified to provide other operational andperformance characteristics that are suited to a particular application.Referring to FIG. 7, there is shown a graph that shows “Efficiency %”versus “Motor Speed (RPM)” for the permanent magnet motor of FIGS. 4 and5A and a prior art fan drive system using an induction motor and VFD.Curve 100 pertains to the permanent magnet motor of FIGS. 4 and 5A andcurve 102 pertains to the prior art fan drive system. As can be seen inthe graph, the efficiency of the permanent magnet motor of FIGS. 4 and5A is relatively higher than the prior art fan drive system for motorspeeds between about 60 RPM and about 200 RPM. The permanent magnetmotor of FIGS. 4 and 5A has relatively low maintenance with a five yearlube interval. The design and architecture of this permanent magnetmotor results in relatively less man-hours associated with service andmaintenance. The bearing L10 life is calculated to be 875,000 hours. Insome instances, this permanent magnet motor can eliminate up to 1000man-hours of annual service and maintenance in a cooling tower. In analternate embodiment, the permanent magnet motor is configured withauto-lube grease options as well as grease fittings depending on theuser.

The high, constant torque of the permanent magnet motor produces therequired fan torque to drive the torque-multiplier device 2002 in orderto accelerate the fan from start-up through the variable speed range.

The permanent magnet motor shown in FIGS. 4A and 5 eliminates widelyvarying fan-motor power consumption problems associated with prior artgearboxes due to frictional losses caused by mechanical condition, wearand tear, and impact of weather on oil viscosity and other mechanicalcomponents.

A typical prior art gearbox system has many moving parts, typically fiverotating shafts, eight bearings, three shaft seals, four gears and twomeshes. The open lubrication design of typical prior art gearbox systemsis not suited for cooling tower service since the open lubricationsystem becomes contaminated from the chemicals, humidity and biologicalcontamination in the cooling tower. However, the variable speed, loadbearing epicyclic drive system of the present invention eliminates thegear box and drive-train as well as shaft, coupling and relateddrive-train vibrations, torsional resonance and other limitationstypically found in prior art drive systems. Furthermore, the variablespeed, load bearing epicyclic drive system of the present inventioneliminates the need for sprag-type clutches typically used to preventopposite rotation of the fans.

Referring to FIG. 2A, torque multiplier-device 2002 can be configured asany one of a variety of suitable drive devices. Suitable drive devicesinclude, but are not limited to, epicyclic traction drives (known asETD) and variable speed infinitely variable transmissions (IVT). Theseare just a few examples. Other suitable drive devices can be used torealize torque multiplier device 2002.

In one embodiment, the torque multiplier device 2002 is configured asthe toroidal traction drive transmission disclosed in U.S. Pat. No.6,126,567, entitled “Toroidal Traction Drive Transmission HavingMultiple Speed Inputs To A Planetary Gear Unit”, the disclosure of whichpatent is hereby incorporated by reference.

In one embodiment, torque multiplier device 2002 comprises a tractionroller transmission which is disclosed in U.S. Pat. No. 4,408,502,entitled “Traction Roller Transmission”, the disclosure of which patentis hereby incorporated by reference.

In one embodiment, torque multiplier device 2002 comprises a tractionroller transmission which is disclosed in U.S. Pat. No. 4,782,723,entitled “Traction Roller Transmission”, the disclosure of which patentis hereby incorporated by reference.

In one embodiment, torque multiplier device 2002 comprises a tractiondrive disclosed in U.S. Pat. No. 4,026,166, entitled “Traction Drive”,the disclosure of which patent is hereby incorporated by reference.

In one embodiment, torque multiplier device 2002 comprises a ballcoupled compound traction drive disclosed in U.S. Pat. No. 4,744,261,entitled “Ball Coupled Compound Traction Drive”, the disclosure of whichpatent is hereby incorporated by reference.

In one embodiment, torque multiplier device 2002 comprises the fixedratio traction roller transmission disclosed in U.S. Pat. No. 4,709,589,entitled “Fixed Ratio Traction Roller Transmission”, the disclosure ofwhich patent is hereby incorporated by reference.

In another embodiment, the torque multiplier device 2002 comprises aratcheting CVT.

As described in the foregoing description, the direct-drive system ofthe present invention may be configured with a combination of any of theforegoing motors and torque multiplier devices. The ensuing descriptionis of different embodiments of the direct-drive system of the presentinvention. Each of these embodiments is now discussed separately and indetail.

Single Speed TEFC Induction Motor and Constant Ratio ETD

FIGS. 2B, 2J and 2K show one embodiment of the direct-drive system 2000of the present invention. In this embodiment, motor 2004 is a TEFC(Totally Enclosed Fan Cooled) induction motor and torque multiplier 2002comprises a constant ratio epicyclic traction drive (ETD). Electrical ACpower is provided to motor 2004 via connector 2008. In this embodiment,the speed of motor 2004 is not variable. Across-the-line starts areattenuated by ETD stall. In one embodiment, a clutch is used. In anotherembodiment, a clutch is not used. In one embodiment, the ETD isconfigured to operate up to 350 HP which exceeds the operationalhorsepower of present-day cooling tower fans. The weight of the ETD istypically 3.0 HP/pound. The weight of the ETD may increase with thehousing, bearings and fan shaft interface so as to ensure structuralintegrity of the fan in order to rotate large diameter fans. However,the overall weight of direct-drive system 2000 is relatively lower thanpresent-day requirements and specifications. The ETD device also allowsa reduction in the size of the induction motor relative to the ETDratio. In order to achieve reverse operation, the wire leads of motor2004 must be reversed by a technician. Once the wire leads are reversed,motor 2004 can operate in reverse at full speed without restrictions. Inanother embodiment, a manually operated reverse switch may be used toreverse the polarity of the input power. In an alternate embodiment,direct-drive system 2000 may incorporate a manual or powered cam,mechanical band or disc to brake the fan at slow speed with motor powerremoved and then hold the fan at 0.0 rpm while a fan locking device isengaged with the fan. Such operation would fully comply with OSHALock-Out-Tag-Out (LOTO) requirements. The reliability of direct-drivesystem 2000 is significantly improved in comparison to prior art fandrive systems using drive shafts and coupling components. Servicing andmaintenance are significantly reduced, if not eliminated altogether,since direct-drive system 2000 is a sealed system. Direct-drive system2000 allows manual de-icing up to 100% speed without durationrestrictions. The general operating temperature of motor 2004 isrelatively lower than the motors in prior art fan drive systems due toreduced loading. FIGS. 2B, 2J and 2K show a constant or fixed ratio ETDdevice which is used to realize torque multiplier device 2002. The ETDdevice comprises a plurality of star rollers 270, 272 and 274 that arelocated within output ring roller 276. The ETD device includes sunroller 278 that engages motor shaft 2006. In this embodiment, the ETDdevice has a fixed or constant ratio between 4:1 and 10:1. Thus, in thisembodiment, the ETD device does not have variable speed. The ETD offersmany advantages:

-   -   i) eliminates gears thereby reducing cost, noise and vibration;    -   ii) sealed lubrication system eliminates lubrication        contamination and frequent changes;    -   iii) tighter component tolerance for longer life and zero        backlash;    -   iv) high rotational accuracy;    -   v) uses planetary mechanism composed of rollers that produce        smooth rotations and eliminates the speed irregularity due to        the high frequency inherent to gear transmissions;    -   vi) uses components that are well supported by mass production        methodologies and are very cost effective to produce; and    -   vii) provides an simple, reliable and economical hybrid direct        drive apparatus that meets height and weight requirements of        existing cooling towers.        In a preferred embodiment, the ETD device is configured as a        sealed gearbox that is not susceptible to the cooling tower        contamination and which utilizes grease and other lubrication        that can last the life of the ETD device without being changed.        The sealed design of the ETD prevents contaminants and moisture        from entering the ETD. The ETD allows for the fan to operate in        reverse (and windmill in reverse when not powered) unlike prior        art gearboxes in which windmilling in reverse is prevented by        accessory devices because the standard gearbox only provides        lubrication in the operating direction. Direct-drive system 2000        is quieter than prior art fan drive systems due to the design of        the constant ratio ETD device. Across-the-line starts do not        cause any damage to direct-drive system 2000 since there are no        shafts or coupling devices. System start-up can also be        accomplished using the ETD either with or without a clutch since        the ETD can be designed to stall at low motor speeds and        positive engagement is not an issue. Vibration switches and        sensors, as well as heat sensors, may be mounted directly to the        ETD device 2002 or motor 2004.        TEFC Induction Motor with VFD and Constant Ratio ETD

Referring to FIG. 2C, in this embodiment, direct-drive system 2000 isconfigured such that motor 2004 comprises a Totally Enclosed Fan Cooled(TEFC) induction motor and torque multiplier device 2002 comprises aconstant ratio epicyclic traction drive (ETD). This Totally Enclosed FanCooled (TEFC) induction motor is an inverter duty motor. This ETD devicehas the same design, structure, operation and function as the constantratio ETD of the embodiment shown in FIG. 2B. Motor 2004 is controlledand powered by programmable variable frequency drive (VFD) device 2012.Specifically, VFD device 2012 provides electrical power and controlsignals to motor 2004 via connector 2008. The control signals can varyand reverse the speed of motor 2004. Therefore, reverse rotation of thefan can be achieved with the VFD device 2012. As will be explained inthe ensuing description, VFD 2012 may be electronically connected to avariable process control system such as a micro-computer, processor,micro-processor, external controller and/or industrial computer in orderto provide automation, monitoring and supervision. When the fan is notpowered, the fan is free to windmill in reverse without restrictions.Flying starts may be implemented when the fan is freely windmilling inreverse because the VFD device 2012 can sense the speed and direction ofthe motor 2004. Braking can be applied to motor 2004 with the VFD device2012. In a preferred embodiment, a load bank or regenerative VFD deviceis used to prevent overheating of the motor. VFD device 2012 allows forprogrammable ramp rates for acceleration and de-acceleration. Thevariable speed characteristic provided by the VFD device 2012 allows upto 100% motor speed in reverse without duration restrictions. Such afeature is very useful for de-icing. In this embodiment, de-icing can bemanual, operator controlled or automatic based on environmentalconditions and/or pre-stored data relating to the design specificationsof the cooling tower. Vibration monitoring, supervision, system-healthand automation may be achieved by a variable process control system thatcan provide control signals to VFD device 2012 and receive electronicdata and sensor signals from VFD device 2012. Such a variable processcontrol system is described in the ensuing description and shown inFIGS. 2L, 3 and 4. In a preferred embodiment, VFD device 2012 is aregenerative VFD. In order to stop rotation of the fan and hold the fanat 0.0 RPM, a load bank or the regenerative VFD device is used whichcauses motor 2004 to function as a generator that generates electricalenergy that is then provided back to the power grid. VFD device 2012allows the speed of motor 2004 to be reduced to 0.0 rpm so that a fanlock can be engaged electrically, pneumatically, hydraulically ormanually for purposes of LOTO and hurricane service. The fan lockremains engaged as all forms of energy are removed from direct-drivesystem 2000 per OSHA requirements. In one embodiment, a cam-lock typebrake is applied to the ETD device ring gear (annulus) and is activatedmanually by a mechanical turn screw or cable. The cam lock type brakecan also be activated by programmable electronic circuitry that controlsan electro-mechanical, pneumatic or hydraulic device such as a solenoidfor braking, holding and locking of the fan. In a further embodiment,braking and holding can be accomplished by using a mechanical band brakethat is located around the annulus of the ETD and is activated manuallyby a mechanical turn screw or cable. The mechanical band-brake can alsobe activated by programmable electronic circuitry that controls anelectro-mechanical, pneumatic or hydraulic device such as a solenoid forbraking and holding the fan for lock-out-tag-out and hurricane service.In yet another embodiment, fan hold is accomplished by anelectro-mechanical device such as a solenoid that is activated byprogrammable electronic circuitry. Emergency braking may be utilizedupon the occurrence of events such as high vibration, power loss,emergency shutdown or operator input. When motor 2004 is allowed tocoast, the fan will slow down normally in under a few minutes andbraking is therefore not normally required. When the motor 2004 isallowed to coast, the rotational speed of the fan will decrease and cometo rest at 0.0 rpm. If the water in the cooling tower cell is left on,the updraft force created by the water will typically cause the fan towindmill in reverse. Prior to entering the fan stack, OSHA requires thatall forms of energy be removed from the system which includes turningoff the water in the cooling tower.

Permanent Magnet Motor with VFD and Constant Ratio ETD

Referring to FIG. 2D, there is shown direct-drive system 2300 inaccordance with another embodiment of the invention. Direct-drive system2300 comprises constant ratio epicyclic traction drive (ETD) device 2302and permanent magnet motor 2304. Permanent magnet motor 2304 includeshousing or casing 2305, rotatable shaft 2306, shown in phantom, and anexternal connector 2308 for receiving electrical signals. Constant ratioepicyclic traction drive (ETD) device 2302 includes output rotatableshaft 2310 and has the same structure and function as ETD device 2002shown in FIGS. 2B and 2C. Motor 2304 is controlled and powered byvariable frequency drive (VFD) device 2312. VFD device 2312 provideselectrical power and control signals to permanent magnet motor 2304 viaconnector 2308 and provides variable speed control of motor 2304. VFDdevice 2312 is configured to be in electronic data signal communicationwith a variable process control system such as a micro-computer,processor, micro-processor, external controller and/or industrialcomputer in order to provide automation, monitoring and supervision. Thefan is free to windmill without restrictions. The VFD device 2312 isconfigured to sense motor speed when the fan is windmilling. The VFDdevice 2312 then applies power to motor 2304 to reduce the rotationalspeed of motor 2304. Flying starts may be implemented when the fan isfreely windmilling in reverse. VFD device 2312 allows for programmableramp rates for acceleration and de-acceleration. The variable speedcharacteristic, provided by the VFD device 2312, allows up to 100% motorspeed in reverse without duration restrictions. Such a feature is veryuseful for de-icing. In this embodiment, de-icing can be manual,operator controlled or automatic based on environmental conditionsand/or pre-stored data relating to the design specifications of thecooling tower. Vibration monitoring, supervision, system-health andautomation may be achieved by a variable process control system that canprovide control signals to VFD device 2312 and receive electronic dataand sensor signals from VFD device 2312. Such a variable process controlsystem is described in the ensuing description and shown in FIGS. 2L, 3and 4. In accordance with the invention, the fan is held at 0.0 RPM bythe permanent magnet motor.

In another embodiment, VFD device 2312 is a regenerative VFD. Forexample, in the embodiment of FIG. 2D, fan braking and fan hold isaccomplished by the regenerative VFD device which causes motor 2304 tofunction as a generator that generates electrical energy that is thenprovided back to the power grid. VFD device 2312 allows the speed ofmotor 2304 to be reduced to 0.0 rpm so that a fan lock can be engagedelectrically, pneumatically, hydraulically or manually to hold the fanat 0.0 RPM for purposes of LOTO and hurricane service. The fan lockremains engaged as all forms of energy are removed from fan driveapparatus 2300 per OSHA requirements. In one embodiment, a cam-lock typebrake is applied to the ETD device ring gear (annulus) and is activatedmanually by a mechanical turn screw or cable. The cam-lock type brakecan also be activated by programmable electronic circuitry that controlsan electro-mechanical, pneumatic or hydraulic device such as a solenoidfor braking, holding and locking of the fan. In a further embodiment,braking and holding can be accomplished by using a mechanical band brakethat is located around the annulus of the ETD and is activated manuallyby a mechanical turn screw or cable. The mechanical band-brake can alsobe activated by programmable electronic circuitry that controls anelectro-mechanical, pneumatic or hydraulic device such as a solenoid forbraking and holding the fan for lock-out-tag-out and hurricane service.In yet another embodiment, fan hold is accomplished by anelectro-mechanical device such as a solenoid that is activated byprogrammable electronic circuitry. Emergency braking may be utilizedupon the occurrence of events such as high vibration, power loss,emergency shutdown or operator input. When motor 2304 is allowed tocoast, the fan will slow down normally in under a few minutes andbraking is therefore not normally required. When the motor 2304 isallowed to coast, the rotational speed of the fan will decrease and cometo rest at 0.0 rpm. The fan may windmill in reverse as a function of theupdraft force created by the operating tower. Braking and fan-lock isfurther discussed in detail the ensuing description. The use ofpermanent magnet motor 2304 provides relatively greater power density,smaller footprint and lighter weight than induction motors. In oneembodiment, permanent magnet motor 2304 is configured as permanentmagnet motor 2004 shown in FIG. 5A and described in the foregoingdescription.

The combination of permanent magnet motor 2304 and the constant ratioETD device 2302 provides a wider range of variable speed control of thecooling system fan. Permanent magnet motor 2304 and VFD device 2312provide reverse operation, flying start, fan braking and fan holdingcombined with fan-lock for lock-out-tag-out. In this embodiment, the ETDdevice 2302 provides torque multiplication to the permanent magnet motor2302 thereby reducing the size, weight and cost of the permanent magnetmotor 2304. The combination of the torque multiplier device 2302 and therelatively smaller permanent magnet motor 2304 reduces motor load andthe total heat generated in motor 2304 while improving performance,energy efficiency and reliability.

Any one of a variety of suitable braking devices can be used to brakethe epicyclic traction drive (ETD) devices of FIGS. 2B, 2C and 2D. Onesuitable braking system is described in U.S. Pat. No. 2,038,443,entitled “Band Brake For Epicyclic Gearing”, the disclosure of whichpatent is hereby incorporated by reference. A suitable cam-brake systemis disclosed in U.S. Pat. No. 1,983,804, entitled “Epicyclic Gearing”,the disclosure of which patent is hereby incorporated by reference.Another suitable braking system is described in U.S. Pat. No. 2,971,406,entitled “Epicyclic Transmission And Control Mechanism Therefor”, thedisclosure of which patent is hereby incorporated by reference. Anothersuitable braking system is described in U.S. Pat. No. 8,187,139,entitled “Planetary Kinematic Arrangement Suitable For Idle EngineStop”, the disclosure of which patent is hereby incorporated byreference. Another suitable braking system is described in U.S. Pat. No.4,114,479, entitled “Epicyclic Gearing”, the disclosure of which patentis hereby incorporated by reference. Another suitable braking system isdescribed in U.S. Pat. No. 3,834,498, entitled “Vehicle Braking ByGearing Lock Up Clutches”, the disclosure of which patent is herebyincorporated by reference. In one embodiment, the ETD of FIGS. 2B, 2Cand 2D has a braking system similar to the braking system described inUnited Kingdom Patent No. GB 2479898A, entitled “Electric Motor HavingAn Annular Brake Disc And Two Braking Devices”, the disclosure of whichpatent is hereby incorporated by reference.

In alternate embodiments of the invention, each ETD device shown inFIGS. 2B, 2C and 2D uses a valving arrangement that enables the starrollers of the ETD to increase friction on the output ring roller (orannulus) to slow and hold the system. The valving arrangement maycomprise springs, or hydraulic solenoids, pneumatic solenoids orelectronic solenoids. Positive locks can then be applied for LOTO andhurricane service. When power to the motor is removed, the star rollerfriction will create drag and impede the forward motion of the rotatingsystem, thereby providing braking.

At relatively slow speed and before fan 12 starts to windmill inreverse, the braking system decreases the fan RPM to 0.0 RPM and holdsthe fan at 0.0 RPM. The fan and motor shaft are then positively lockedvia mechanical levers, cables, electronic solenoids or pneumatic orhydraulic means so as to allow all electrical power to be removed fromthe fan drive apparatus of the present invention while the lockingdevices remain engaged. The fan drive apparatus must be re-energizedwith electrical power in order to deactivate the programmable locks.

In the embodiments of FIGS. 2B, 2C and 2D, the fan braking function canalternately be accomplished by the ETD device. This would require usinga programmable controller to control the star rollers of the ETD deviceto increase friction thereby slowing the system. The power of the motoris simultaneously decreased so as to allow the star rollers to bring thefan to rest and then hold the fan at 0.0 RPM (i.e. Fan-Hold mode). TheVFD device senses the motor speed at all times. In this alternateembodiment, a DAQ (Data Acquisition Device) is in electronic datacommunication with the VFD and the programmable controller. In avariation of this alternate embodiment, an integrated inverter andcontroller control both the motor and ETD in the same manner as atransmission control module. Such a transmission control module isdisclosed in international application publication no. WO 9414226 andUnited Kingdom Patent No. GB2462940, which published internationalapplication and patent are discussed in the ensuing description.

Single Speed TEFC Motor and Variable Speed CVT with IntegratedController

Referring to FIG. 2E, there is shown direct-drive system 2400 inaccordance with another embodiment of the present invention.Direct-drive system 2400 comprises a single speed TEFC motor 2402 and avariable speed continuously variable transmission (CVT) 2404. CVT 2404includes housing 2405 and integrated controller 2406. Integratedcontroller 2406 can receive electronic control signals via externalelectrical connector 2408. Motor 2402 includes housing 2410 androtatable shaft 2412. CVT 2404 includes rotatable output shaft 2414.Since motor 2402 is a single speed motor, a variable frequency drivedevice is not used. The motor 2402 includes a power connector 2416 andreceives AC electrical power through power connector 2416. The rotationof motor 2402 can be reversed by manually reversing the wire leads whichcarry the AC power. Fan 12 is free to windmill in either directionwithout any restrictions. CVT 2404 is a variable speed CVT and the speedof the CVT 2404 is controlled by the integrated controller 2406. In oneembodiment, control signals from a variable process control system areprovided to integrated control 2406 via connector 2408. Such a variableprocess control system is described in the ensuing description.

In alternate embodiment, direct-drive system 2400 uses the permanentmagnet motor shown in FIGS. 5A and 5B instead of a single speed TEFCmotor. However, it is to be understood that direct-drive system 2400 canbe configured with any of the motors described in the foregoingdescription.

The variable speed CVT 2404 is specifically configured to be a loadbearing variable speed CVT 2404 that bears fan loads and provides therequired torque and rotational speed. Variable speed CVT 2004 can beconfigured as a pulley-type CVT, a toroidal CVT, a CVT with AdaptiveShift Control (ASC) or a variator.

CVT 2004 can be configured with a reverse mode so the rotation of themotor does not have to be reversed.

CVT 2004 can be programmed for a flying start.

CVT 2004 can be programmed for fan acceleration rates.

CVT 2004 can provide resistance braking for programmed de-accelerationand “Park”.

CVT 2004 can be configured to provide regenerative braking. In such anembodiment, the motor is preferably a permanent magnet motor or aninverter duty induction motor.

Motor 2402 is braked and held via mechanical means. Integratedcontroller 2406 controls the variator or equivalent device (spheres) soas to actively brake and hold. Planetary gears can then provide apositive lock to direct-drive system 2400 similar to when an automobiletransmission is shifted into “Park”. Vibration monitoring isaccomplished through the use of sensor switches mounted to the exteriorhousing of direct-drive system 2400. Vibration sensors can be locatedinternal to direct-drive system 2400 or located on the exterior ofdirect-drive system 2400.

In this embodiment, across-the-line starts are accomplished with aclutch.

Variable Speed TEFC Motor with Integrated Controller and Inverter andVariable Speed CVT

Referring to FIG. 2F, there is shown direct-drive system 2500 inaccordance with another embodiment of the invention. Direct-drive system2500 comprises motor 2502 and torque multiplier device 2504. The motor2502 comprises a variable speed Totally Enclosed Fan Cooled (TEFC)induction motor. The motor 2502 includes rotatable shaft 2506 andhousing 2508. Torque multiplier device 2504 comprises a variable speed,continuously variable transmission (CVT). CVT 2504 includes housing orcasing 2509 and rotatable output shaft 2510. Motor 2502 is controlledand powered by internal integrated controller 2512 and inverter 2514.Electrical power and control signals are provided to controller 2512 andinverter 2514 via connector 2516. Inverter 2514 provides the properelectrical power to motor 2502 and controller 2512 provides variablespeed control of motor 2502. The variable speed features of motor 2502and CVT 2504 provide a better speed match and wider ratio. In oneembodiment, a variable process control system provides control signalsto controller 2512. Such a variable process control system is discussedin the ensuing description. Controller 2512 is programmable and allowsfor programmable ramp rates for acceleration and de-acceleration andflying starts. In a preferred embodiment, a clutch is also used forflying starts. Programmed flying starts are also possible in thisembodiment and can be utilized when fan 12 is freely windmilling inreverse. The variable speed capabilities of motor 2502 and CVT 2504enable reverse operation of direct-drive system 2500 withoutrestrictions on speed or duration. Such a feature is very useful forde-icing. In this embodiment, de-icing can be manual, operatorcontrolled or automatic based on environmental conditions and/orpre-stored data relating to the design specifications of the coolingtower. Vibration monitoring, supervision, system-health and automationcan be achieved by a variable process control system that is shown inFIGS. 2L, 3 and 4 and described in the ensuing description. Fan brakingand fan hold may be achieved with a load bank or a regenerative VFDdevice. The load bank or regenerative VFD device causes motor 2502 tofunction as a generator and thus generate electrical energy that isdistributed back to the power grid. Controller 2512 allows the speed ofmotor 2502 to be reduced to 0.0 rpm so that a fan lock can be engagedelectrically, pneumatically, hydraulically or manually for purposes ofLOTO and hurricane service. The fan lock remains engaged when allelectrical power is removed from direct-drive system 2500 per OSHArequirements. In one embodiment, a cam-lock type brake is applied tomotor shaft 2506 and is activated manually by a mechanical turn screw orcable. The cam-lock type brake can also be activated by programmableelectronic circuitry that controls an electro-mechanical, pneumatic orhydraulic device such as a solenoid for braking, holding and locking ofthe fan. In a further embodiment, braking and holding can beaccomplished by a mechanical band brake that is located around motorshaft 2506 and is activated manually by a mechanical turn screw orcable. The mechanical band-brake can also be activated by programmableelectronic circuitry that controls an electro-mechanical, pneumatic orhydraulic device such as a solenoid. In yet another embodiment, fan holdis accomplished by an electro-mechanical device such as a solenoid thatis activated by programmable electronic circuitry. Emergency braking maybe utilized upon the occurrence of events such as high vibration, powerloss, emergency shutdown or operator input. When motor 2502 is allowedto coast, the fan will slow down normally in under a few minutes andbraking is therefore not normally required. When the motor 2502 isallowed to coast, the fan will eventually come to rest at 0.0 rpm. Thefan will then windmill in reverse as a function of the updraft forcecreated by the operating tower. The “coasting” characteristics of motor2502 may be programmed into the operational logic of the variableprocess control system (see FIGS. 2L, 3 and 4) as a function of energysavings. Controller 2512 also provides for fan control, supervision andautomation especially when in electronic signal communication with theaforementioned variable process control system.

In alternate embodiment, direct-drive system 2500 uses the permanentmagnet motor shown in FIGS. 5A and 5B instead of the variable speed TEFCmotor. However, it is to be understood that direct-drive system 2500 canbe configured with any of the motors described in the foregoingdescription.

It is to be understood that integrated controllers and inverters such asintegrated controller 2512 and inverter 2514, respectively, may be usedin any of the embodiments of the load bearing direct drive system of thepresent invention that utilize a variable speed motor.

Single Speed TEFC Motor and Variable Speed IVT with IntegratedController

Referring to FIG. 2G, there is shown direct-drive system 2600 inaccordance with another embodiment of the invention. Direct-drive system2600 comprises motor 2602 and torque multiplier device 2604. The motor2602 comprises a single speed Totally Enclosed Fan Cooled (TEFC)inverter rated induction motor. The motor 2602 has a rotatable shaft2606, shown in phantom, and housing 2608. Torque multiplier device 2604is a variable speed IVT (infinitely variable transmission) and hashousing or casing 2609 and rotatable output shaft 2610. The speed of IVT2604 is controlled by controller 2612. Controller 2612 is alsoconfigured to receive external control signals via connector 2614. Poweris applied to motor 2602 via connector 2616. The rotation of variablespeed IVT 2604 can be reversed by controller 2612. In order to reversethe speed of motor 2602, the wire leads on motor 2602 must be manuallyreversed. In an alternate embodiment, a manually operated reverse switchis used to reverse the speed of motor 2602. In this embodiment, flyingstarts are programmable and no clutch is required. Programmed flyingstarts may be achieved when fan 12 is freely windmilling. Once the wireleads of motor 2602 are reversed, the variable speed capability of IVT2604 allows for reverse operation of direct-drive system 2600 withoutrestrictions on speed or duration. Such a feature is very useful forde-icing. In this embodiment, de-icing can be manual,operator-controlled or automatic based on environmental conditionsand/or pre-stored data relating to the design specifications of thecooling tower. Vibration monitoring, supervision, system-health andautomation are may be achieved by the variable process control systemwhich is shown in FIGS. 2L, 3 and 4 and described in the ensuingdescription. Direct-drive system 2600 allows for fan braking and fanhold. Controller 2612 allows the speed of IVT 2604 to be reduced to 0.0rpm so that a fan lock can be engaged electrically, pneumatically,hydraulically or manually. The fan lock remains engaged while allelectrical power is removed from direct-drive system 2600. In oneembodiment, a cam-lock type brake is applied to motor shaft 2606 and isactivated manually by a mechanical turn screw or cable. The cam-locktype brake can also be activated by programmable electronic circuitrythat controls an electro-mechanical, pneumatic or hydraulic device suchas a solenoid for braking, holding and locking of the fan. In a furtherembodiment, braking and holding can be accomplished by a mechanical bandbrake that is located around motor shaft 2606 and is activated manuallyby a mechanical turn screw or cable. The mechanical band-brake can alsobe activated by programmable electronic circuitry that controls anelectro-mechanical, pneumatic or hydraulic device such as a solenoid forbraking and holding the fan. In yet another embodiment, fan hold isaccomplished by an electro-mechanical device such as a solenoid that isactivated by programmable electronic circuitry. Emergency braking may beutilized upon the occurrence of events such as high vibration, powerloss, emergency shutdown or operator input. When motor 2602 is allowedto coast, the fan will slow down normally in under a few minutes andbraking is therefore not normally required. When the motor 2602 isallowed to coast, the fan will eventually come to rest at 0.0 rpm. Then,the fan will windmill in reverse as a function of the updraft forcecreated by the operating tower. The “coasting” characteristics of motor2602 may be programmed into the operational logic of the variableprocess control. Controller 2612, when linked to the aforementionedvariable process control system (see FIGS. 2L, 3 and 4), providesautomation, supervision and continuous monitoring of the operatingcharacteristics of direct-drive system 2600.

In alternate embodiment, direct-drive system 2600 uses the permanentmagnet motor shown in FIGS. 5A and 5B instead of the single speed TEFCmotor. However, it is to be understood that direct-drive system 2600 canbe configured with any of the motors described in the foregoingdescription.

IVT 2604 is specifically designed and configured to be a load bearinginfinitely variable transmission and to provide the required torque androtational speed for the particular application.

In one embodiment, IVT 2604 is configured to combine an ETD or planetarydrive with a CVT. There are many benefits and advantages in using suchan IVT. Specifically, motor 2602 can be continuously operated at optimumconditions and at maximum efficiency. For any given power demand, IVT2604 will operate motor at a pre-determined torque and speed therebyensuing maximum efficiency. Typically, this means that the motor 2602operates at low speeds with reduced friction losses and at high torquewith reduced throttling losses. The IVT 2604 dispenses with the need forinefficient starting devices such as torque converters.

IVT 2604 can be configured with a reverse mode so the rotation of themotor does not have to be reversed.

IVT 2604 can be programmed for a flying start.

IVT 2604 can be programmed for fan acceleration rates.

IVT 2604 can provide resistance braking for programmed de-accelerationand “Park”.

IVT 2004 can provide regenerative braking if properly equipped. In suchan embodiment, the motor is preferably a permanent magnet motor or aninverter duty induction motor.

Variable Speed TEFC Inverter Rated Induction Motor with IntegratedInverter IVT

Referring to FIG. 2H, there is shown direct-drive system 2700 inaccordance with another embodiment of the invention. Direct-drive system2700 comprises motor 2702. Motor 2702 has rotatable shaft 2704, shown inphantom, and housing or casing 2705. Motor 2702 comprises a variablespeed Totally Enclosed Fan Cooled (TEFC) inverter rated induction motor.Direct-drive system 2700 further comprises torque multiplier device2706. Torque multiplier device 2706 comprises a variable speed IVT. IVT2706 has rotatable output shaft 2708 that is configured to be connectedto a fan. IVT 2706 includes housing or casing 2709. Motor 2702 hasinternal controller 2710 and inverter 2712. Controller 2710 and inverter2712 are integrated into the motor structure. Inverter 2712 receivescontrol signals from controller 2710. Controller 2710 is configured toreceive control signals via connector 2714 and controls the speed ofmotor 2702. Controller 2710 controls the speed of motor 2702. Inverter2712 receives electrical power through connector 2714 and provides theelectrical power to motor 2702. Motor 2702 and IVT 2706 are bothvariable speed devices and therefore, achieve a greater speed range andwider torque ratio. Controller 2710 is programmable and allows forprogrammable ramp rates for acceleration and de-acceleration and flyingstarts. Fan 12 may freely windmill without restriction. Programmedflying starts may be implemented when fan 12 is freely windmilling.Controller 2710 allows direct-drive system 2700 to operate in reverse upto 100% speed without duration restrictions. Such a feature is veryuseful for de-icing. In this embodiment, de-icing can be manual,operator controlled or automatic based on environmental conditionsand/or pre-stored data relating to the design specifications of thecooling tower. Vibration monitoring, supervision, system-health andautomation may be achieved by a variable process control system such asthe type shown in FIGS. 2L, 3 and 4 and described in the ensuingdescription. Direct-drive system 2700 allows the fan to be braked andheld. Specifically, controller 2710 allows the speed of motor 2702 to bereduced to 0.0 rpm so that a fan lock can be engaged electrically,pneumatically, hydraulically or manually for purposes of LOTO andhurricane service. The fan lock remains engaged while all forms ofenergy are removed from fan direct-drive system 2700. In one embodiment,a cam lock type brake is applied to motor shaft 2704 and is activatedmanually by a mechanical turn screw or cable. The cam-lock type brakecan also be activated by programmable electronic circuitry that controlsan electro-mechanical, pneumatic or hydraulic device such as a solenoidfor braking, holding and locking the fan. In a further embodiment,braking and holding can be accomplished by a mechanical band-brake thatis located around motor shaft 2704 and is activated manually by amechanical turn-screw or cable. The mechanical band-brake can also beactivated by programmable electronic circuitry that controls anelectro-mechanical, pneumatic or hydraulic device such as a solenoid forbraking and holding the fan. In yet another embodiment, fan hold isaccomplished by an electro-mechanical device such as a solenoid that isactivated by programmable electronic circuitry. Emergency braking may beutilized upon the occurrence of events such as high vibration, powerloss, emergency shutdown or operator input. When the motor 2702 isallowed to coast, the fan will slow down normally in under a few minutesand braking is therefore not normally required. When the motor 2702 isallowed to coast, the fan will eventually come to rest at 0.0 rpm. Thefan may windmill as a function of the updraft force created by thecooling tower. The “coasting” characteristics of motor 2702 may beprogrammed into the operational logic of a variable process controlsystem. Such a variable process control system is shown in FIGS. 2L, 3and 4.

In alternate embodiment, direct-drive system 2700 uses the permanentmagnet motor shown in FIGS. 5A and 5B instead of the variable speed TEFCinverter rated induction motor. However, it is to be understood thatdirect-drive system 2700 can be configured with any of the motorsdescribed in the foregoing description.

IVT 2706 can be configured with a reverse mode so the rotation of themotor does not have to be reversed.

IVT 2706 can be programmed for a flying start.

IVT 2706 can be programmed for fan acceleration rates.

IVT 2706 can provide resistance braking for programmed de-accelerationand “Park”.

IVT 2706 can provide regenerative braking if properly equipped. In suchan embodiment, the motor is preferably a permanent magnet motor or aninverter duty induction motor.

Another example of a fan lock mechanism which may be used with thedirect-drive system of the present invention is shown in FIGS. 21A, 21Band 21C. Motor 2004, shown in FIG. 5A, is used in the ensuingdescription for purposes of describing this fan lock mechanism. The fanlock mechanism is a solenoid-actuated pin-lock system and comprisesenclosure or housing 1200, which protects the inner components fromenvironmental conditions, stop-pin 1202 and solenoid or actuator 1204.The solenoid or actuator 1204 receives an electrical actuation signalfrom DAQ device 200 (see FIGS. 2 and 4) when it is desired to preventfan rotation. The fan lock mechanism may be mounted on the drive portionof motor shaft 2006 that is adjacent the fan hub, or it may be mountedon the lower, non-drive end portion 25 of motor shaft 2006. The phrase“non-drive end” refers to the lower end portion of motor shaft 2006which is not physically connected to the torque multiplier device. FIG.21B shows solenoid 1204 in the activated state so that stop-pin 1202engages rotatable shaft 2006 of motor 2004 so as to prevent rotation ofshaft 2006 and the fan. In FIG. 21A, solenoid 1204 is deactivated sothat stop pin 1202 is disengaged from rotatable motor shaft 2006 so asto allow rotation of motor shaft 2006 and the fan. FIG. 21C shows thefan-lock mechanism on both the upper, drive end of motor shaft 2006, andthe lower, non-drive end portion 25 of motor shaft 2006. In an alternateembodiment, the fan-lock mechanism shown in FIGS. 21A and 21B can becable-actuated. In a further embodiment, the fan-lock mechanism shown inFIGS. 21A and 21B is actuated by a flexible shaft. In yet anotherembodiment, the fan-lock mechanism shown in FIGS. 21A and 21B ismotor-actuated.

Referring to FIG. 22, there is shown a caliper-type fan-lock mechanismwhich can be used with the direct-drive system of the present invention.Once again, motor 2004, which is shown in FIG. 5A, is used in thisensuing description for purposes of describing this caliper-typefan-lock mechanism. This caliper-type fan-lock mechanism compriseshousing or cover 1300 and a caliper assembly, indicated by referencenumbers 1302 and 1303. The caliper type fan lock mechanism also includesdiscs 1304 and 1305, flexible shaft cover 1306 and a shaft or threadedrod 1308 that is disposed within the flexible shaft cover 1306. Thecaliper-type fan lock mechanism further includes fixed caliper block1310 and movable caliper block 1311. In an alternate embodiment, a cableis used in place of the shaft or threaded rod 1308. In alternateembodiments, the fan lock mechanism can be activated by a motor (e.g.screw activated) or a pull-type locking solenoid. FIG. 22 shows the fanlock mechanism mounted on top of the motor 2004 so it can engage theupper portion of motor shaft 2006. FIG. 23 shows the fan lock mechanismmounted at the bottom of motor 2004 so the fan-lock mechanism can engagethe lower, non-drive end portion 25 of motor shaft 2006. Thiscaliper-type fan-lock mechanism comprises housing or cover 1400 and acaliper assembly, indicated by reference numbers 1402 and 1404. Thiscaliper-type fan-lock mechanism includes disc 1406, flexible shaft cover1410 and shaft or threaded rod 1408 that is disposed within the flexibleshaft cover 1410.

Referring to FIG. 25, there is shown a band-type fan-lock mechanism thatcan be used with motor 2004. This band-type fan lock mechanism compriseshousing or cover 1600, flexible shaft cover 1602 and a shaft or threadedrod 1604 that is disposed within the flexible shaft cover 1604. Theband-type fan lock mechanism further includes fixed lock bands 1606 and1610 and lock drum 1608. In an alternate embodiment, a cable is used inplace of the shaft or threaded rod 1604. In alternate embodiments, theband-type fan lock mechanism can be activated by a motor (e.g. screwactivated) or a pull-type locking solenoid. FIG. 25 shows the fan lockmechanism mounted on top of the motor 2004 so it can engage the upperportion 2006A of motor shaft 2006. FIG. 24 shows the fan lock mechanismmounted at the bottom portion of motor 20 so the fan lock mechanism canengage the lower, non-drive end portion 25 of motor shaft 2006.

In another embodiment, the fan lock is configured as the fan lockdescribed in U.S. Patent Application Publication No. 2006/0292004, thedisclosure of which published application is hereby incorporated byreference.

Alternate Direct-Drive Apparatuses of the Present Invention

Referring to FIG. 2I, there is shown direct-drive system 3000 inaccordance with another embodiment of the present invention.Direct-drive system 3000 comprises housing or casing 3001 rotatableoutput shaft 3002 that is configured to be connected to a fan of acooling system such as a wet-cooling tower, ACHE, chiller, HVAC systemsand blowers. Output shaft 3002 may be connected to any fan. Direct-drivesystem 3000 includes connector 3004 for receiving power signals andcontrol signals. In one embodiment, direct-drive system 3000 includeselectronic controller 3006 shown in phantom. In another embodiment,direct-drive system 3000 further includes electronic inverter 3008 shownin phantom. In such an embodiment, controller 3006 and inverter 3008 arein electrical signal communication with each other and connector 3004.However, it is to be understood that electronic controller 3006 and/orinverter 3008 may or may not be used, depending upon the specificconfiguration of direct-drive system 3000.

In one embodiment, direct-drive system 3000 comprises a hydrostatic CVT.

In one embodiment, direct-drive system 3000 comprises a system similarto the integrated hydrostatic transaxle disclosed in U.S. Pat. No.5,897,452 entitled “Integrated Hydrostatic Transaxle With ControlledTraction Differential”, the disclosure of which patent is herebyincorporated by reference.

In one embodiment, direct-drive system 3000 comprises a fulltransmission.

In one embodiment, direct-drive system 3000 comprises an alternatesealed gearmotor with gearbox (e.g. Siemens Motox).

In one embodiment, direct-drive system 3000 comprises a planetarygearbox.

In one embodiment, direct-drive system 3000 comprises an infinitelyvariable transmission (IVT). This can be a pulley-type IVT or an equalmechanical advantage simple machine. In this embodiment, thetransmission comprises a variator coupled to an epicyclic gear, whichmixes variator and engine speeds to produce the resultant speed. Thistransmission also enables reverse, forward and even zero-output speedwithout a launch device such as a clutch.

In one embodiment, direct-drive system 3000 comprises a system similarto an Agro Tractor transmission that utilizes an infinitely variabletransmission (IVT) in combination with hydraulic pumps.

In one embodiment, direct-drive system 3000 comprises a sphericalinfinitely variable transmission (IVT). Such a suitable spherical IVT ismanufactured by Fallbrook Technologies Inc. of San Diego, Calif. andmarketed under the trademark NuVinci® Technology. The spherical IVT is acontinuously variable planetary transmission (CVP) that combines theadvantages of a toroidal traction (spheres) continuously variabletransmission (CVT) with the advantages of a planetary gear arrangement.

In one embodiment, direct-drive system 3000 comprises a variable speeddrive which is disclosed in U.S. Pat. No. 3,727,473, entitled “VariableSpeed Drive Mechanisms”, the disclosure of which patent is herebyincorporated by reference.

In one embodiment, direct-drive system 3000 comprises an electromotivedrive. A suitable electromotive drive is disclosed in U.S. Pat. No.7,632,203, entitled “Electromotive Drives”, the disclosure of whichpatent is hereby incorporated by reference.

In one embodiment, direct-drive system 3000 comprises the continuouslyvariable traction drive disclosed in U.S. Patent Application PublicationNo. US2011/0034295, entitled “High Speed And Continuously VariableTraction Drive”, the disclosure of which published application is herebyincorporated by reference.

In one embodiment, direct-drive system 3000 comprises a hydro-mechanicalinfinitely variable transmission (IVT). A suitable hydro-mechanical(IVT) is disclosed in U.S. Pat. No. 7,261,663, entitled “ContinuouslyVariable Planetary Set”, the disclosure of which patent is herebyincorporated by reference.

In one embodiment, direct-drive system 3000 comprises the continuouslyvariable transmission disclosed in U.S. Pat. No. 8,142,323, entitled“Continuously Variable Transmission”, the disclosure of which patent isincorporated by reference.

In one embodiment, direct-drive system 3000 comprises the continuouslyvariable transmission disclosed in U.S. Patent Application PublicationNo. US2009/0312145, the disclosure of which published patent applicationis hereby incorporated by reference. The drive apparatus disclosed inthis published patent application is also known as a Fallbrook NuVinci®Delta Series™ Assembly Drive.

In one embodiment, direct-drive system 3000 comprises a magneticcontinuously variable transmission or magnetic CVT (also known as mCVT).One suitable magnetic CVT is described in U.S. Pat. No. 7,982,351,entitled “Electrical Machines”, the disclosure of which patent is herebyincorporated by reference. Such a magnetic CVT is a variable magnetictransmission that provides an electrically controllable gear ratio. Themagnetic CVT functions as a power split device and can match a fixedinput speed from a prime-mover to a variable load by importing/exportingelectrical power through a variator path. Such magnetic CVTs are alsodescribed in the presentation paper entitled “Recent Developments InElectric Traction Drive Technologies”, authored by J. Wang of Universityof Sheffield, United Kingdom and presented at the “Joint EC/EPoSSWorkshop on Smart Systems for Full Electric Vehicle.” The magnetic CVTdescribed in U.S. Pat. No. 7,982,351 is manufactured by Magnomatics Ltd.and generally includes a magnet gear which can utilize as a gear-reduceror a step-up gear, and (b) Pseudo Direct Drive System (also known as aPDD® system). The Pseudo Direct Drive System is an extremely compactmagnetic and mechanical integration of a low ratio magnetic gear and abrushless permanent magnet motor/generator. This integrated machine hasa torque density, which is several times greater than a high performancepermanent magnet machine, and results in a compact electrical drive thatdoes not require any ancillary lubrication or cooling systems.

In another embodiment, direct-drive system 3000 comprises a magneticgear. A suitable magnetic gear is disclosed in US Patent ApplicationPublication No. US2012/0094555, entitled “Electric Marine PropulsionDevice With Integral Magnetic Gearing”, the disclosure of whichpublished patent application is hereby incorporated by reference.

In another embodiment, direct-drive system 3000 comprises a magneticgear. A suitable magnetic gear is disclosed in U.S. Pat. No. 7,973,441,entitled “Magnetic Gear”, the disclosure of which patent is herebyincorporated by reference.

In another embodiment, direct-drive system 3000 comprises a magneticgear. A suitable magnetic gear is disclosed in US Patent ApplicationPublication No. US2011/0127869, entitled “Magnetic Gear”, the disclosureof which published patent application is hereby incorporated byreference.

In another embodiment, direct-drive system 3000 comprises variablemagnetic gears. Suitable variable magnetic gears are disclosed in USPatent Application Publication No. US2011/0037333, entitled “VariableMagnetic Gear”, the disclosure of which published application is herebyincorporated by reference.

In one embodiment, direct-drive system 3000 comprises a stepper motorwith an integrated inverter. A suitable stepper motor with integratedinverters is disclosed in published United Kingdom patent applicationno. GB2462940, entitled “Electric Machine Having Controller For EachCoil Set”, the disclosure of which published patent application ishereby incorporated by reference. Another suitable stepper motor with anintegrated inverter is disclosed in published United Kingdom patentapplication no. GB2477128, entitled “Power Source Switching ArrangementFor Electric Vehicle”, the disclosure of which published patentapplication is hereby incorporated by reference. Another suitablestepper motor with an integrated inverter is disclosed in the publishedinternational application having international publication no. WO9414226, entitled “Motor System With Individually Controlled RedundantWindings”, the disclosure of which published application is herebyincorporated by reference.

In one embodiment, direct-drive system 3000 comprises an automotivesupercharger. A suitable automotive supercharger is disclosed in U.S.Pat. No. 7,703,283, entitled “Automotive Air Blower”. Another suitableautomotive supercharger is disclosed in U.S. Patent ApplicationPublication No. 20100186725, entitled “Automotive Blower”, thedisclosure of which U.S. patent application publication is herebyincorporated by reference.

In one embodiment, direct-drive system 3000 comprises a switchedreluctance machine. A suitable switched reluctance machine is disclosedin U.S. Pat. No. 4,998,052, entitled “Gearless Direct Drive SwitchedReluctance Motor For Laundry Application”, the disclosure of whichpatent is hereby incorporated by reference. Another suitable switchedreluctance machine is disclosed in U.S. Pat. No. 6,700,284, entitled“Fan Assembly Including A Segmented Stator Switched Reluctance FanMotor”, the disclosure of which patent is hereby incorporated byreference. Another suitable switched reluctance machine is disclosed inU.S. Pat. No. 7,202,626, entitled “Variable Speed Drive For A ChillerSystem With A Switched Reluctance Motor”, the disclosure of which patentis hereby incorporated by reference.

In one embodiment, direct-drive system 3000 comprises a system similarto a super-turbocharger having a high speed traction drive and acontinuously variable transmission. Examples of such super-turbochargersare disclosed in U.S. Patent Application Publication Nos. US2010/0031935and US2010/0199666, the disclosures of which published applications arehereby incorporated by reference.

When direct-drive system 3000 is configured as a continuously variabletransmission, a suitable CVT control system that may be applied todirect-drive system 3000 is disclosed in U.S. Pat. No. 5,938,557,entitled “CVT Control System”, the disclosure of which patent is herebyincorporated by reference. Another suitable system and method forcontrolling a CVT is disclosed in U.S. Pat. No. 8,108,108, entitled“Method Of Controlling A Continuously Variable Transmission”, thedisclosure of which patent is hereby incorporated by reference. Anothersuitable system and method for controlling a CVT is disclosed in U.S.Pat. No. 7,160,226, entitled “Continuously Variable Transmission AndMethod Of Operation Thereof”, the disclosure of which patent is herebyincorporated by reference.

When direct-drive system 3000 is configured as a continuously variabletransmission, the AC electrical generation system disclosed in U.S. Pat.No. 7,915,748, entitled “AC Electrical Generation System”, may be usedwith direct-drive system 3000. The disclosure of U.S. Pat. No. 7,915,748is hereby incorporated by reference.

When direct-drive system 3000 utilizes or is configured as a variator, asuitable variator control system that may be applied to direct-drivesystem 3000 is disclosed in U.S. Pat. No. 6,030,310, entitled “VariatorControl System”, the disclosure of which patent is hereby incorporatedby reference.

All of the embodiments described in the foregoing description that use aVFD are capable of braking when a fan windmills. When the fan iswindmilling, the VFD can determine the direction of rotation and speedof the windmilling fan and can apply motor braking to limit the speed ofthe fan.

Any of the embodiments described in the foregoing description that use aVFD are capable of condensation control. When the permanent magnet motoris at 0.0 RPM, the VFD can energize the coils of the motor withoutexciting the rotor in order to provide heat to the motor andcondensation control and also prevent the motor from freezing. The motorinternal and external temperature sensors provide feedback to the DAQdevice for real time motor temperature control with respect toenvironmental stress and required motor operating temperatures.

In alternate embodiment, the load bearing direct drive system comprisesa continuously variable transmission (CVT) and a single speed motorwherein the single speed motor drives the CVT but only the CVT iscontrolled with the required control and power electronics. There is novariable speed control of the single speed motor.

In a further embodiment, the load bearing direct drive system comprisesan infinitely variable transmission (IVT) and a single speed motorwherein the single speed motor drives the IVT but only the IVT iscontrolled with the required control and power electronics. There is novariable speed control of the single speed motor.

Referring to FIG. 2M, there is shown load bearing, direct-drive system3500 in accordance with another embodiment of the present invention.Direct-drive system 3500 comprises structural frame 3502 and loadbearing, epicyclic traction drive (ETD) device 3504. Epicyclic tractiondrive (ETD) device 3504 is attached to structural frame 3502. In oneembodiment, structural frame 3502 is attached to mounting plate 3506. Inan alternate embodiment, mounting plate 3506 is not used. Fan shaft 3508is engaged with epicyclic traction drive (ETD) 3504. Thus, fan shaft3508 is driven by epicyclic traction drive (ETD) device 3504.Direct-drive system 3500 further comprises motor 3510. Motor 3510includes shaft 3512, shown in phantom, which drives the epicyclictraction drive (ETD) device 3504. In one embodiment, motor 3510 is acommercially available single speed TEFC motor. Epicyclic traction drive(ETD) 3504 bears all loads created by the fan, whether the fan isrotating or stationary. Direct-drive system 3500 may include any of thepower and control electronics shown in FIGS. 2C-2I and described in theforegoing description.

Referring to FIG. 2N, there is shown load bearing, direct-drive system3600 in accordance with another embodiment of the present invention.Direct-drive system 3600 comprises load bearing motor 3602. In oneembodiment, motor 3602 is a single speed, load bearing TEFC motor. Inone embodiment, load bearing motor 3602 is attached to mounting plate3604. In another embodiment, mounting plate 3604 is not used. Loadbearing motor 3602 comprises shaft 3606, shown in phantom. Direct-drivesystem 3600 further comprises load bearing, epicyclic traction drive(ETD) device 3608. Motor shaft 3606 is engaged with and drives epicyclictraction drive (ETD) device 3608. Fan shaft 3610 is engaged withepicyclic traction drive (ETD) device 3608 and epicyclic traction drive(ETD) device 3608 drives fan shaft 3610. Epicyclic traction drive (ETD)device 3608 is configured to bear loads created by the fan when the fanis rotating or stationary. Therefore, motor 3602 and epicyclic tractiondrive (ETD) device 3608 share the loads created by the fan. In apreferred embodiment, motor 3602 and epicyclic traction drive (ETD)device 3608 are field interchangeable. Direct-drive system 3600 mayinclude any of the power and control electronics shown in FIGS. 2C-2Iand described in the foregoing description.

Referring to FIG. 2O, there is shown load bearing, direct drive system3700 in accordance with another embodiment of the invention. Apparatus3701, shown in phantom, is located within housing or structural frame3702 and comprises an epicyclic traction drive (ETD) device and a motor.Apparatus 3701 is an integrated system that does not have fieldinterchangeable components. Therefore, the motor and the epicyclictraction drive (ETD) device are not separate components. Fan shaft 3706is engaged with and driven by direct-drive system 3700. The entiredirect drive system 3700 is a load bearing system and bears all of theloads imparted by a fan, whether the fan is rotating or stationary.Direct-drive system 3700 may include any of the power and controlelectronics shown in FIGS. 2C-2I and described in the foregoingdescription. In one embodiment, the structural frame of housing 3702 isattached to mounting plate 3704. In another embodiment, mounting plate3704 is not used.

Referring to FIG. 2P, there is shown load bearing, direct drive system3800 in accordance with a further embodiment of the present invention.Direct-drive system 3800 comprises housing or structural frame 3802which is attached to a mounting plate 3804. In an alternate embodiment,mounting plate 3804 is not used. Direct-drive system 3800 furthercomprises load bearing system 3806. Fan shaft 3808 is integrated withand driven by load bearing system 3806. Load bearing system 3806 isconfigured to bear all of the loads created by the fan, whether the fanis rotating or stationary. Direct drive system 3800 further comprisesepicyclic traction drive (ETD) device 3810 which has a shaft 3812, shownin phantom, that is engaged with and drives load bearing system 3806.Direct-drive system 3800 further comprises motor 3814. Motor 3814 hasshaft 3816, shown in phantom, which is engaged with and drives epicyclictraction drive device 3810. In this embodiment, motor 3814 can be acommercially available, single speed TEFC motor. Epicyclic tractiondrive (ETD) device 3810 and motor 3814 generate the required torque todrive load bearing system 3806.

It is to be understood that in other embodiments, the direct-drivesystems of FIGS. 2M, 2N, 2O and 2P may be modified to replace theepicyclic traction drive (ETD) devices with any of the torque multiplierdevices described in the foregoing description.

In an alternate embodiment, the epicyclic traction drive (ETD) devicecan be configured as a step-up device wherein it multiplies the inputspeed of the motor. Such alternate embodiments would have applicationsin wind turbine generators and other applications.

Referring to FIGS. 2L, 3 and 4, there is shown the variable processcontrol system of the present invention for managing the operation offans and pumps in cooling apparatus 10. Cooling apparatus 10 can beconfigured as a wet-cooling tower, blower, induced draft air-cooled heatexchanger (ACHE), chiller or a HVAC system which are commonly used tocool liquids used in an industrial process, e.g. petroleum refinery,chemical plant, etc. One example of a wet-cooling tower is described ininternational application no. PCT/US2008/077338, published underinternational publication no. WO 2009/048736. The disclosure ofinternational publication no. WO 2009/048736 is hereby incorporated byreference. The same wet-cooling tower is described in U.S. Pat. No.8,111,028, entitled “Integrated Fan Drive System For Cooling Tower”, thedisclosure of which patent is hereby incorporated by reference. Oneexample of an air-cooled heat exchanger (ACHE) is described ininternational application no. PCT/US2009/037242, published underinternational publication no. WO 2009/120522. The disclosure ofinternational publication no. WO 2009/120522 is hereby incorporated byreference. The same type of air-cooled heat exchanger (ACHE) isdisclosed in U.S. Pat. No. 8,188,698, entitled “Integrated Fan-DriveSystem For Air-Cooled Heat-Exchanger (ACHE)”, the disclosure of whichpatent is hereby incorporated by reference. For purposes of describingthe system of the present invention, cooling apparatus 10 is describedas being a wet-cooling tower. An ACHE system is described later in theensuing description. Cooling apparatus 10 comprises fan 12 and fan stack14. As is known in the field, cooling towers may utilize fill materialwhich is described in the aforementioned international publication no.WO 2009/048736. Fan 12 comprises hub 16 and a plurality of fan blades 18that are connected to and extend from hub 16. Cooling apparatus 10further comprises direct-drive system 2000 shown in FIG. 2A. Forpurposes of describing the variable process control system, direct-drivesystem 2000 is described in terms of motor 2004 being the permanentmagnet motor shown in FIGS. 4 and 5A. In FIG. 4, the torque multiplierdevice 2002 is not shown in order to facilitate viewing of motor 2004.

Referring to FIGS. 2L and 4, the variable process control system of thepresent invention further comprises industrial computer 300. Industrialcomputer 300 is preferably co-located with DAQ device 200. Industrialcomputer 300 is in data communication with data bus 302. Data bus 302 isin data communication with DAQ device 200. Industrial computer 300 isresponsible for post-processing of performance data of the cooling towerand the system of the present invention. Included in thispost-processing function are data logging and data reduction. Industrialcomputer 300 is programmed with software programs, an FFT algorithm andother algorithms for processing system performance data, environmentaldata and historical data to generate performance data reports, trenddata and generate historical reports based on performance data itreceives from DAQ device 200. Industrial computer 300 also stores datainputted by the operators through the plant Distributed Control System(DCS) 315. Such stored data includes fan maps, fan pitch, Cooling TowerDesign Curves, and Thermal Gradient analysis data. The wet-bulbtemperature data is continually calculated from relative humidity andambient temperature and is inputted into industrial computer 300. Userinput 304 (e.g. keyboard) and display 306 (e.g. display screen) are indata signal communication with industrial computer 300. An operator usesuser input 304 to input commands into industrial computer 300 togenerate specific types of processed data. Industrial computer 300displays on display 306 real-time data relating to the operation of thecooling tower and the system of the present invention, including directdrive system 2000. Industrial computer 300 is also used to program newor revised data into DAQ device 200 in response to changing conditionssuch as variable process demand, motor status, fan condition, includingfan pitch and balance, and sensor output signals. The sensor outputsignals are described in the ensuing description. In a preferredembodiment, industrial computer 300 is in data signal communication withhost server 310. Host service 310 is in data signal communication withone or more remote computers 312 that are located at remote locations inorder to provide off-site monitoring and analysis. Industrial computer300 is also in data signal communication with the plant DistributedControl System (DCS) 315, shown in phantom in FIGS. 2L and 3. Users oroperators can input data into DCS 315 including revised temperatureset-points, or revised pump flow rates or even change the plant loadsetting from full plant load to part-plant load. This revisedinformation is communicated to industrial computer 300 which then routesthe information to DAQ device 200. DAQ device 200 and industrialcomputer 300 provide real-time cooling performance monitoring, real-timecondition fault monitoring and autonomous control of fan speed.

In a preferred embodiment, industrial computer 300 receives continuousweather data from the national weather surface or NOAA. Industrialcomputer 300 receives this data directly via an Internet connection, orfrom the data via host server 310, or from on-site weather station 316.Industrial computer 300 converts such weather data to a data form thatcan be processed by DAQ device 200. As shown in FIG. 2L, the variableprocess control system of the present invention includes on-site weatherstation 316 which is in data signal communication with the Internet andDAQ device 200. On-site weather station 316 comprises components andsystems to measure parameters such as wind speed and direction, relativehumidity, ambient temperature, barometric pressure and wet-bulbtemperature. These measured parameters are used by industrial computer300 to determine Cooling Tower Thermal Capacity and also to determinethe degree of icing on the tower. These measure parameters are also usedfor analysis of the operation of the cooling tower. On-site weatherstation 316 also monitor's weather forecasts and issues alerts such ashigh winds, freezing rain, etc.

In one embodiment, the VFD device 22, DAQ device 200, industrialcomputer 300 and power electronics are located in Motor ControlEnclosure (MCE) 26 (see FIG. 12A). The Distributed Control System (DCS)315 is electronically connected to industrial computer 300 at MCE 26.Operators would be able to log onto industrial computer 300 for trendinginformation and alerts. DAQ device 200 automatically generates andissues alerts via email messages or SMS text messages to multiplerecipients, including the Distributed Control System (DCS) 315, withattached documents and reports with live and historical information aswell as alarms and events.

In one embodiment, industrial computer 300 is programmed to allow anoperator to shut down or activate the direct drive fan system from aremote location.

Referring to FIGS. 2L, 3 and 4, VFD device 22 controls the speed,direction and torque of fan 12. DAQ device 200 is in electrical signalcommunication with VFD device 22 and provides signals to the VFD device22 which, in response, outputs electrical power signals to motor 2004 inaccordance with a desired speed, torque and direction. Specifically, theDAQ device 200 generates control signals for VFD device 22 that definethe desired fan speed (RPM), direction and torque of motor 2004. DAQdevice 200 is also programmed to issue signals to the VFD device 22 tooperate the fan 12 in a normal mode of operation referred to herein as“energy optimization mode”. This “energy optimization mode” is describedin detail in the ensuing description. When acceleration of motor 2004 isdesired, DAC device 200 outputs signals to VFD device 22 that define aprogrammed rate of acceleration. Similarly, when deceleration of motor2004 is desired, DAQ device 200 outputs signals to VFD device 22 thatdefine a programmed rate of deceleration. If it is desired to quicklydecrease the RPM of motor 2004, DAQ device 200 outputs signals to VFDdevice 22 that define a particular rate of deceleration that continuesuntil the motor comes to a complete stop (e.g. 0.0 RPM).

DAQ device 200 provides several functions in the system of the presentinvention. DAQ device 200 receives electronic data signals from allsensors and variable speed pumps (discussed in the ensuing description).DAQ device 200 also continuously monitors sensor signals sent to theaforesaid sensors to verify that these sensors are working properly. DAQdevice 200 is programmed to issue an alert is there is a lost sensorsignal or a bad sensor signal. DAQ device 200 automatically adjusts theRPM of motor 2004 in response to the sensor output signals. Accordingly,the system of the present invention employs feedback loops tocontinuously adjust the RPM of motor 2004, and hence fan 12, in responseto changes in the performance of the fan, cooling tower characteristics,process load, thermal load, pump flow-rate and weather and environmentalconditions. The feedback loops are shown in FIG. 3. DAQ device 200 isprogrammable and can be programmed with data defining or representingthe tower characteristics, trend data, geographical location of thecooling tower, weather and environmental conditions. DAQ device 200 isconfigured with internet compatibility (TCP/IP compatibility) andautomatically generates and issues email messages or SMS text messagesto multiple recipients, including the Distributed Control System (DCS)315, with attached documents and reports with live and historicalinformation as well as alarms and events. In a preferred embodiment, DAQdevice 200 comprises multiple physical interfaces including Ethernet,RS-232, RS-485, fiber optics, Modbus, GSM/GPRS, PSTN modem, private linemodem and radio. Preferably, DAQ device 200 has SCADA compatibility. Inone embodiment, DAQ device 200 is configured as a commercially availabledata acquisition system. In an alternate embodiment, DAQ device 200 isconfigured to transmit data to industrial computer 300 via telemetrysignals.

Referring to FIG. 2L, power cable 105 has one end that is terminated atmotor 2004. Specifically, power cable 105 is factory sealed to ClassOne, Division Two, Groups B, C and D specifications and extends throughthe motor housing 21 and is terminated within the interior of motorhousing 21 during the assembly of motor 2004. Therefore, when installingmotor 2004 in a cooling apparatus, it is not necessary for techniciansor other personnel to electrically connect power cable 105 to motor2004. The other end of power cable 105 is electrically connected tomotor disconnect junction box 106. Power cable 105 is configured as anarea classified, VFD rated and shielded power cable. Motor disconnectjunction box 106 includes a manual emergency shut-off switch. Motordisconnect junction box 106 is primarily for electrical isolation. Powercable 105 comprises three wires that are electrically connected to theshut-off switch in motor-disconnect junction box 106. Power cable 107 isconnected between the shut-off switch in motor-disconnect junction box106 and VFD device 22. Power cable 107 is configured as an areaclassified, VFD rated and shielded power cable. The electrical powersignals generated by VFD device 22 are carried by power cable 107 whichdelivers these electrical power signals to junction box 106. Motor powercable 105 is connected to power cable 107 at junction box 106. Thus,motor power cable 105 then provides the electrical power signals tomotor 2004.

Referring to FIGS. 2L and 4, quick-disconnect adapter 108 is connectedto motor housing 21. In one embodiment, quick-disconnect adapter 108 isa Turck Multifast Right Angle Stainless Connector with Lokfast Guard,manufactured by Turck Inc. of Minneapolis, Minn. The sensors internal tomotor housing 21 are wired to quick-disconnect adapter 108. Cable 110 isconnected to quick-disconnect adapter 108 and to communication datajunction box 111. Communication data junction box 111 is located on thefan deck. The electronic components in communication data junction box111 are powered by a voltage source (not shown). Cable 110 is configuredas an area-classified multiple connector, shielded flexible controlcable. Cable 112 is electrically connected between communication datajunction box 111 and data acquisition device 200 (referred to herein as“DAQ device 200”). In one embodiment, cable 112 is configured as anEthernet cable. As described in the foregoing description, VFD device 22is in data communication with Data Acquisition Device (DAQ) device 200.VFD device 22 and DAQ device 200 are mounted within Motor ControlEnclosure 26 (see FIGS. 12A and 4). A Motor Control Enclosure typicallyis used for a single motor or fan cell. The MCE 26 is typically locatedon the fan deck in close proximity to the motor. The MCE 26 houses VFDdevice 22, DAQ device 200, industrial computer 300 and the powerelectronics. In one embodiment, MCE 26 is a NEMA 4X Rated Cabinet. VFDdevice 22 and DAQ device 200 are discussed in detail in the ensuingdescription.

Referring to FIGS. 2L, 4 and 5A, shaft 2006 of permanent magnet motor2004 rotates when the appropriate electrical signals are applied topermanent magnet motor 2004. Rotation of shaft 2004 drives torquemultiplier device 2002 which, in turn, causes rotation of fan 12. VFDdevice 22 comprises a plurality of independently controlled programmablevariable frequency drive (VFD) devices 23A, 23B, 23C, 23D and 23E (seeFIGS. 4 and 26). VFD device 23A controls motor 2004. The remaining VFDdevices control the permanent magnet motors in the variable speed pumps(see FIG. 26). This aspect of the invention is described in the ensuingdescription. DAQ device 200 provides control signals to each of the VFDdevices 23A, 23B, 23C, 23D and 23E. These features are discussed laterin the ensuing description. VFD device 23A provides the appropriateelectrical power signals to motor 2004 via cables 107 and 105. There istwo-way data communication between VFD device 22 and DAQ device 200. DAQdevice 200 comprises a controller module which comprises a computerand/or microprocessor having computer processing capabilities,electronic circuitry to receive and issue electronic signals and abuilt-in keyboard or keypad to allow an operator to input commands. Inone embodiment, DAQ device 200 comprises a commercially available CSESemaphore TBox RTU System that comprises a data acquisition system,computer processors, communication modules, power supplies and remotewireless modules. The CSE Semaphore TBox RTU System is manufactured byCSE Semaphore, Inc. of Lake Mary, Fla. In a preferred embodiment, theCSE Semaphore TBox RTU System is programmed with a commerciallyavailable computer software packages known as Dream Report™ and TView™which analyze collected data. In an alternate embodiment, the CSESemaphore TBox RTU System is programmed with commercially availablesoftware known as TwinSoft™. In DAQ device 200 is described in detail inthe ensuing description. VFD device 22 comprises a variable frequencycontroller 120 and signal interface 122. VFD device 22 controls thespeed and direction (i.e. clockwise or counterclockwise) of permanentmagnet motor 2004. AC voltage signals are inputted into variablefrequency controller 120 via input 124. Variable frequency controller120 outputs the power signals that are inputted into motor 2004 viapower cables 107 and 105. Referring to FIG. 4, signal interface 122 isin electrical signal communication with DAQ device 200 via data signalbus 202 and receives signals to start, reverse, accelerate, decelerate,coast, stop and hold motor 2004 or to increase or decrease the RPM ofmotor 2004. In a preferred embodiment, signal interface 122 includes amicroprocessor. Signal interface 122 outputs motor status signals overdata bus 202 for input into DAQ device 200. These motor status signalsrepresent the motor speed (RPM), motor current (ampere) draw, motorvoltage, motor power dissipation, motor power factor, and motor torque.

VFD device 23A measures motor current, motor voltage and the motor powerfactor that are used to calculate energy consumption. VFD device 23Aalso measures motor speed, motor power and motor torque. VFD device 23Aalso measures Run Time/Hour Meter in order to provide a time stamp andtime-duration value. The time stamp and time-duration are used byindustrial computer 300 for failure and operational life analysis, FFTprocessing, trending, and predicting service maintenance. Industrialcomputer 300 is discussed in detail in the ensuing description.

Referring to FIGS. 4 and 26, VFD devices 23B, 23C, 23D and 23E outputelectrical power signals 1724, 1732, 1740 and 1754, respectively, forcontrolling the variable speed pumps 1722, 1730, 1738 and 1752,respectively, that pump liquid (e.g. water) to and from the coolingtower. This aspect of the present invention is discussed in detail inthe ensuing description.

Referring to FIG. 8, there is shown a partial view of a cooling tower 10that utilizes the direct-drive fan system of the present invention. Inthis embodiment, cooling tower 10 comprises a wet-cooling tower. Thewet-cooling tower comprises fan 12, fan stack 14, fan hub 16, and fanblades 18, all of which were discussed in the foregoing description. Fanstack 14 is supported by fan deck 250. Fan stack 14 can be configured tohave a parabolic shape or a cylindrical (straight) shape as is wellknown in the field. Motor 2004 is supported by a metal frame or ladderframe or torque tube that spans across a central opening (not shown) infan deck 250. Motor shaft 2006 is configured as a keyed shaft and isdirectly connected to fan hub 16 (see FIG. 14). Power cables 105 and107, motor-disconnect junction box 106 and quick-disconnect connector108 were previously discussed in the foregoing description. Power cable107 is connected between motor-disconnect junction box 106 and variablefrequency controller 120 of VFD device 22 (see FIGS. 2L and 4) which islocated inside MCE 26. Referring to FIGS. 2K, 4 and 8, cable 110 iselectrically connected between quick-disconnect adapter 108 andcommunication data junction box 111. These signals are fed to DAQ device200 via cable 112. DAQ device 200 and industrial computer 300 arelocated in MCE 26. (see FIG. 2L).

The direct-drive system of the present invention may also be used todrive fans in ACHE systems. Referring to FIG. 10A, there is shown anair-cooled heat exchanger (ACHE) that utilizes the direct-drive system2000 of the present invention. This particular ACHE is an induced-draftACHE. The remaining portion of the ACHE is not shown since the structureof an ACHE is known in the art. The ACHE comprises tube bundle 800,vertical support columns 801A and 801B, parabolic fan stack 802,horizontal support structure 804, support members 805 and fan assembly12. Fan assembly 12 comprises fan hub 16 and fan blades 18 that areattached to fan hub 16. Vertical shaft 806 is connected to fan hub 16and coupled to output shaft 2010 of direct-drive system 2000 withcoupling 808. Direct-drive system 2000 is connected to and supported byhorizontal member 804. Additional structural supports 810A and 810B addfurther stability to direct-drive system 2000. Direct-drive system 2000is configured with a pair of separate bearing systems 850 and 852 whichare driven by coupling 808. The separate bearing systems 850 and 852allow the ACHE support structure to bear either full or partial fanloads.

Referring to FIG. 10A, as described in the foregoing description, oneend of power cable 105 is terminated at direct-drive system 2000 and theother end of power cable 105 is electrically connected to the motordisconnect junction box 106. Power cable 107 is connected between motordisconnect junction box 106 and VFD device 22. As described in theforegoing description, cable 110 is electrically connected betweenquick-disconnect adapter 108 and communication data junction box 111,and cable 112 is electrically connected between communication datajunction box 111 and DAQ device 200. VFD device 22 and DAQ device 200are mounted within Motor Control Enclosure (MCE) 26 which is not shownin FIG. 10A but which was described in the foregoing description. It isto be understood that the direct-drive system of the present inventionmay be used to drive the fan in any of the ACHE systems described inU.S. Pat. No. 8,188,698, entitled “Integrated Fan-Drive System ForAir-Cooled Heat-Exchanger (ACHE)”, the disclosure of which patent ishereby incorporated by reference. Referring to FIG. 10B, there is showna forced draft ACHE 4000 that uses direct-drive system 2000. Supportstructure 4002 comprises support members 4004 and columns 4006. Tubebundle 4008 is supported by support structure 4002. Direct-drive system2000 is supported by and connected to support members 4004. Direct-drivesystem 2000 drives fan 12. Fan 12 is positioned beneath tube bundle 4008and rotates within fan stack 4010. Fan stack 4010 is attached to supportstructure 4002. Output shaft 2010 of direct-drive system 2000 isconnected to fan hub 16. FIG. 11 shows another induced-draft ACHE 5000which has support structure 5002. Support structure 5002 comprises upperstructure 5004 and vertical columns 5006. Tube bundle 5008 is attachedto vertical columns 5006. Direct-drive system 2000 is connected to upperstructure 5004 and is oriented upside down. Output shaft 2010 ofdirect-drive system 2000 is connected to fan hub 12. Direct-drive system2000 and fan 12 are positioned above tube bundle 5008. Fan 12 rotateswithin fan stack 5012 which is attached to support structure 5002.

The direct-drive system of the present invention is a sealed system andtherefore can be used in wet applications, such as a wet-cooling tower,or in dry applications, such as the ACHE system, or in a combinationwet/dry system such as a hybrid cooling tower.

The direct-drive system of the present invention may be mounted orpositioned in any orientation. For example, the direct-drive system ofthe present invention may be positioned below the fan, in which case theshaft of the fan is vertically oriented upward. In another example, thedirect-drive system of the present invention may be positioned above thefan, in which case the shaft is vertically oriented downward. In afurther example, the direct-drive system of the present invention ispositioned so that the shaft is horizontal. In other examples, thedirect-drive system of the present invention is positioned so that theshaft is at angle between 0° and 90°.

Referring back to FIGS. 2L, 3 and 4, the feedback loops effectcontinuous monitoring of the operation of direct-drive system 2000, fan12 and the variable speed pumps. The feedback loops also effectautomatic adjustment of the RPM of direct-drive system 2000 and of thepermanent magnet motors in the variable speed pumps (see FIG. 26). Thefeedback loops shown in FIG. 3 allow direct-drive system 2000 to beoperated in any one of a plurality of modes of operation which arediscussed in the ensuing description.

The various modes of operation of the variable process control system ofthe present invention are described in the ensuing description. Theensuing description is in terms of load bearing direct-drive system 2000being configured with the permanent magnet motor 2004 shown in FIGS. 5Aand 5B and wherein motor 2004 drives torque multiplier device 2002.However, it is to be understood that the ensuing description of thevarious modes of operation is applicable to all of the embodiments ofthe load bearing direct-drive system described in the foregoingdescription.

Flying Start Mode

The variable process control system of the present invention isconfigured to operate in a “Flying Start Mode” of operation withinfinite control of fan 12. A flow chart of this mode of operation isshown in FIG. 16B. In this mode of operation, VFD device 22 senses thedirection of the fan 12 (i.e. clockwise or counter-clockwise) and then:(a) applies the appropriate signal to motor 2004 in order to slow fan 12to a stop (if rotating in reverse), or (b) ramps motor 2004 to speed, or(c) catches fan 12 operating in the correct direction and ramps tospeed. The graph in FIG. 16C illustrates the “Flying Start Mode”. Thenomenclature in FIG. 16C is defined as follows:

“A” is a desired, fixed or constant speed for motor 2004 (i.e. constantRPM);

“B” is the Time in seconds for VFD device 22 to accelerate motor 2004from 0.0 RPM to desired RPM (i.e. Ramp-Up Time).

“C” is the Time in seconds for VFD device 22 to decelerate motor 2004from the desired RPM to 0.0 RPM (i.e. Ramp-Down Time).

“Angle D” is the acceleration time in RPM/second and is defined as“cos(A/B)”;

“Angle E” is the deceleration time in RPM/second and is defined as“cos(A/C)”;

Angle D and Angle E may be identical, but they do not have to be.

The “Flying Start” mode may be implemented if any of the followingconditions exist:

Condition #2: Motor 2004 is detected at 0.0 RPM. The VFD device 22accelerates motor 2004 to desired RPM in “B” seconds.

Condition #1: Motor 2004 is detected running in reverse direction. TheVFD device 22 calculates time to decelerate motor 2004 to 0.0 RPM atrate of D. Motor 20 is then accelerated to “A” RPM. Total time for motorto reach “A” RPM is greater than “B” seconds.

Condition #3: Motor 2004 is detected running in forward direction. VFDdevice 22 calculates position of motor 2004 on ramp and uses rate “D” toaccelerate motor to “A” RPM. Total time for motor 2004 to reach “A” RPMis less than “B” seconds.

Condition #4: Motor 2004 is detected running greater than “A” RPM. VFDdevice 22 calculates time to decelerate motor 2004 to “A” RPM using rateE.

This Flying Start mode of operation is possible because the bearingdesign of permanent magnet motor 2004 allows windmilling in reverse.

Soft Start Mode

The variable process control system of the present invention isconfigured to operate in a “Soft Start Mode” of operation. In this modeof operation, with VFD device 22 is programmed to initiate accelerationin accordance with predetermined ramp rate. Such a controlled rate ofacceleration eliminates breakage of system components with “across theline starts”. Such “breakage” is common with prior art gearbox fan drivesystems.

Hot Day Mode

Another mode of operation that can be implemented by the variableprocess control system of the present invention is the “hot day” mode ofoperation. The “hot day” mode of operation is used when more cooling isrequired and the speed of all fans is increased to 100% maximum fan tipspeed. The “hot day” mode of operation can also be used in the event ofan emergency in order to stabilize an industrial process that mayrequire more cooling.

Energy Optimization Mode

The variable process control system of the present invention isconfigured to operate in an “Energy Optimization Mode”. In this mode ofoperation, the fan 12 and the variable speed pumps 1722, 1730, 1738, and1752 (see FIG. 26) are operated to maintain a constant basintemperature. The control of fan speed is based upon the cooling towerdesign, predicted and actual process demand and historical environmentalconditions with corrections for current process and environmentalconditions. Industrial computer 300 uses historical data to predict theprocess demand for a current day based on historical process demandpatterns and historical environmental conditions, and then calculates afan speed curve as a function of time. The calculated fan speed curverepresents the minimal energy required to operate the fan throughout thevariable speed range for that current day in order to meet the constantbasin temperature demand required by the industrial process. In realtime, the variable process control system processes the actualenvironmental conditions and industrial process demand and providespredictions and corrections that are used to adjust the previouslycalculated fan speed curve as a function of time. VFD device 22 outputselectrical power signals in accordance with the corrected fan speedcurve. The system utilizes logic based on current weather forecasts,from on-site weather station 316, as well as historical trendspertaining to past operating data, past process demand, and pastenvironmental conditions (e.g. weather data, temperature and wet-bulbtemperature) to calculate the operating fan speed curve. In this EnergyOptimization Mode, the fan operation follows the changes in the dailywet-bulb temperature. Fan operation is represented by a sine wave over a24 hour period, as shown in the top portion of the graph in FIG. 9,wherein the fan speed transitions are smooth and deliberate and follow atrend of acceleration and deceleration. In FIG. 9, the “Y” axis is“Motor Speed” and the “X” axis is “Time”. The fan speed curve in the topportion of the graph in FIG. 9 (Energy Optimization Mode” is directlyrelated to wet-bulb temperature. The duration of time represented by the“X” axis is a twenty-four period. The variable process control system ofthe present invention uses a Runge-Kutter algorithm that analyzeshistorical process demand and environmental stress as well as currentprocess demand and environmental stress to generate a fan speed curvethat results in energy savings. This control of the fan speed istherefore predictive in nature so as to optimize energy consumption asopposed to being reactive to past data. Such a process minimizes theenergy consumed in varying the fan speed. Such smooth fan speedtransitions of the present invention are totally contrary to the abruptfan speed transitions of the prior art fan drive systems, which areillustrated at the bottom of the graph in FIG. 9. The fan speedtransitions of the prior art fan drive system consist of numerous,abrupt fan-speed changes occurring over a twenty-four period in shortspurts. Such abrupt fan speed changes are the result of the prior artvariable speed logic which is constantly “switching” or accelerating anddecelerating the fan to satisfy the basin temperature set point.

Therefore, the Energy Optimization Mode of the present invention usesthe cooling tower data, process demand, geographical location data,current environmental data and historical trends to predict fan speedaccording to loading so as to provide a smooth fan-speed curvethroughout the day. Such operation minimizes the fan speed differentialand results in optimized energy efficiency.

Soft-Stop Mode

The variable process control system and motor 2004 of the presentinvention are configured to operate in a “Soft-Stop Mode” of operation.In this mode of operation, DAQ device 200 provides signals to VFD device22 that cause VFD device 22 to decelerate motor 2004 under power inaccordance with a predetermined negative ramp rate to achieve acontrolled stop. This mode of operation also eliminates breakage ofand/or damage to system components. This “Soft-Stop Mode” quickly bringsthe fan to a complete stop thereby reducing damage to the fan. Theparticular architecture of motor 2004 allows the fan to be held at 0.0RPM to prevent the fan from windmilling in reverse. Such a “Soft StopMode” of operation is not found in prior art fan drive systems usinginduction motors.

Fan Hold Mode

The variable process control system and motor 2004 of the presentinvention are configured to operate in a “Fan-Hold Mode”. This mode ofoperation is used during a lock-out, tag-out (LOTO) procedure which isdiscussed in detail in the ensuing description. “If a LOTO procedure isto be implemented, then motor 2004 is first brought to 0.00 RPM usingthe “Soft-Stop Mode”, then the “Fan-Hold Mode” is implemented in orderto prevent the fan from windmilling. Fan-hold is a function of thedesign of permanent magnet motor 2004. DAQ device 200 provides signalsto VFD device 22 to cause VFD device 22 to decelerate motor 2004 underpower at a predetermined negative ramp rate to achieve a controlled stopof fan 12 in accordance with the “Soft-Stop Mode”. VFD device 22controls motor 2004 under power so that fan 12 is held stationary. Next,the motor shaft 2006 is locked with a locking mechanism (as will bedescribed in the ensuing description). Next, all forms of energy (e.g.electrical power) are terminated according to the Lock-Out-Tag-Out(LOTO) procedure and fan 12 is then secured. In prior art drive systemsusing induction motors, attempting to brake and hold a fan wouldactually cause damage to the induction motor. However, such problems areeliminated with the “Soft-Stop and “Fan-Hold Modes”.

Reverse Operation Mode

The variable process control system and motor 2004 of the presentinvention can also implement a “Reverse Operation Mode”. In this mode ofoperation, permanent magnet motor 2004 is operated in reverse. This modeof operation is possible since there are no restrictions or limitationson motor 2004 unlike prior art gearbox fan drive systems which have manylimitations (e.g. lubrication limitations). The unique bearing system ofmotor 2004 allows unlimited reverse rotation of motor 2004.Specifically, the unique design of motor 2004 allows design torque andspeed in both directions.

Reverse Flying Start Mode

The variable process control system and motor 2004 of the presentinvention can also implement a “Reverse Flying-Start Mode” of operation.In this mode of operation, the Flying Start mode of operation isimplemented to obtain reverse rotation. The motor 2004 is firstdecelerated under power until 0.00 RPM is attained than then reverserotation is immediately initiated. This mode of operation is to possiblesince there are no restrictions or limitations on motor 2004 in reverse.This mode of operation is useful for de-icing.

Lock-Out Tag Out

In accordance with the invention, a particular Lock-Out Tag-Out (LOTO)procedure is used to stop fan 12 in order to conduct maintenance on fan12. A flow-chart of this procedure is shown in FIG. 16A. Initially, themotor 2004 is running at the requested speed. In one embodiment, inorder to initiate the LOTO procedure, an operator uses the built-inkeypad of DAQ device 200 to implement “Soft-Stop Mode” so as to causemotor 2004, and thus fan 12, to decelerate to 0.0 RPM. Once the RPM ofmotor 2004 is at 0.0 RPM, the “Fan-Hold Mode” is implemented to allowVFD device 22 and motor 2004 to hold the fan 12 at 0.0 RPM under power.A fan lock mechanism is then applied to motor shaft 2006. All forms ofenergy (e.g. electrical energy) are then removed so as to lock out VFD22 and motor 2004. Operator or user interaction can then take place. Thefan lock mechanism can be either manually, electrically, mechanically orpneumatically operated, and either mounted to or built-in to motor 2004.This fan lock will mechanically hold and lock the motor shaft 2006thereby preventing the fan 12 from rotating when power is removed. Sucha fan lock can be used for LOTO as well as hurricane service. Fan lockconfigurations are discussed in the ensuing description. Once themaintenance procedures are completed on the fan or cooling tower, allsafety guards are replaced, the fan lock is released and the mechanicaldevices are returned to normal operation. The operator then unlocks andpowers up VFD device 22. Once power is restored, the operator uses thekeypad of DAQ device 200 to restart and resume fan operation. This LOTOcapability is a direct result of motor 2004 being directly coupled tofan hub 16. The LOTO procedure provides reliable control of fan 12 andis significantly safer than prior art techniques. This LOTO procedurecomplies with the National Safety Council and OSHA guidelines forremoval of all forms of energy.

De-Ice Mode

The variable process control system and motor 2004 are also configuredto implement a “De-Ice Mode” of operation wherein the fan is operated inreverse. Icing of the fans in a cooling tower may occur depending uponthermal demand (i.e. water from the industrial process and the returndemand) on the tower and environmental conditions (i.e. temperature,wind and relative humidity). Operating cooling towers in freezingweather is described in the January, 2007 “Technical Report”, publishedby SPX Cooling Technologies. The capability of motor 2004 to operate inreverse in order to reverse the fan direction during cold weather willde-ice the tower faster and completely by retaining warm air in thecooling tower as required by the environmental conditions. Motor 2004can operate in reverse without limitations in speed and duration.However, prior art gear boxes are not designed to operate in reverse dueto the limitations of the gearbox's bearing and lubrication systems. Oneprior art technique is to add lubrication pumps (electrical and gerotor)to the prior art gearbox in order to enable lubrication in reverseoperation. In order to solve the problems of icing in a manner thateliminates the problems of prior art de-icing techniques, the variableprocess control system of the present invention implements an automaticde-icing operation without operator involvement and is based upon thecooling tower thermal design, thermal gradient data, ambienttemperature, relative humidity, wet-bulb temperature, wind speed anddirection. Due to the bearing design and architecture of motor 2004 anddesign torque, fan 12 is able to rotate in either direction (forward orreverse). This important feature enables the fan 12 to be rotated inreverse for purposes of de-icing. DAQ device 200 and VFD device 22 areconfigured to operate motor 2004 at variable speed which will reduceicing in colder weather. DAQ device 200 is programmed with temperatureset points, tower design parameters, plant thermal loading, andenvironmental conditions and uses this programmed data and the measuredtemperature values provided by the temperature sensors to determine ifde-icing is necessary. If DAQ device 200 determines that de-icing isnecessary, then the de-icing mode is automatically initiated withoutoperator involvement. When such environmental conditions exist, DAQdevice 200 generates control signals that cause VFD device 22 to rampdown the RPM of motor 2004 to 0.0 RPM. The Soft-Stop Mode can be used toramp the motor RPM down to 0.00 RPM. Next, the motor 2004 is operated inreverse so as to rotate the fan 12 in reverse so as to de-ice thecooling tower. The Reverse Flying Start mode can be used to implementde-icing. Since motor 2004 does not have the limitations of prior artgearboxes, supervision in this automatic de-ice mode is not necessary.Upon initiation of de-icing, DAQ device 200 issues a signal toindustrial computer 300. In response, display screen 306 displays anotice that informs the operators of the de-icing operation. Thisde-icing function is possible because motor 2004, as shown in FIGS. 5Aand 5B, comprises a unique bearing design and lubrication system thatallows unlimited reverse operation (i.e. 100% fan speed in reverse)without duration limitations. The unlimited reverse operation incombination with variable speed provides operators or end users withinfinite speed range in both directions to match ever changingenvironmental stress (wind and temperatures) while meeting processdemand. Since DAQ device 200 can be programmed, the de-icing program maybe tailored to the specific design of a cooling tower, the plant thermalloading and the surrounding environment. In a preferred embodiment, DAQdevice 200 generates email or SMS text messages to notify the operatorsof initiation of the de-ice mode. In a preferred embodiment, DAQ device200 generates a de-icing schedule based on the cooling tower design, thereal time temperature, wet-bulb temperature, wind speed and direction,and other environmental conditions. In an alternate embodiment,temperature devices maybe installed within the tower to monitor theprogress of the de-icing operation or to trigger other events. Thevariable process control system of the present invention is configuredto allow an operator to manually initiate the De-Ice mode of operation.The software of the DAQ device 200 and industrial computer 300 allowsthe operator to use either the keypad at the DAQ device 200, or userinput device 304 which is in data signal communication with industrialcomputer 300. In alternate embodiment, the operator initiates theDe-Icing mode via Distributed Control System 315. In such an embodiment,the control signals are routed to industrial computer 300 and then toDAQ device 200.

In a multi-cell system, there is a separate VFD device for eachpermanent magnet motor but only one DAQ device for all of the cells.This means that every permanent magnet motor, whether driving a fan or avariable speed pump, will receive control signals from a separate,independent, dedicated VFD device. Such a multi-cell system is describedin detail in the ensuing description. The DAQ device is programmed withthe same data as described in the foregoing description and furtherincludes data representing the number of cells. The DAQ device controlseach cell individually such that certain cells may be dwelled, idled,held at stop or allowed to windmill while others may function in reverseat a particular speed to de-ice the tower depending upon the particulardesign of the cooling tower, outside temperature, wet bulb, relativehumidity, wind speed and direction. Thus, the DAQ device determineswhich cells will be operated in the de-ice mode. Specifically, DAQdevice 200 is programmed so that certain cells will automatically startde-icing the tower by running in reverse based upon the cooling towerdesign requirements. Thus, the fan in each cell can be operatedindependently to retain heat in the tower for de-icing while maintainingprocess demand.

The temperature sensors in the cooling towers, whether single fan ormulti-cell, provide temperature data to the DAQ device 200 which thenprocesses these signals to determine if the De-Ice mode should beimplemented. In a multi-cell tower, certain cells may need de-icing andother cells may not. In that case, the DAQ device sends the de-icingsignals to only the VFDs that correspond to fan cells requiringde-icing.

The DAQ device is also programmed to provide operators with the optionof just reducing the speed of the fans in order to achieve some level ofde-icing without having to stop the fans and then operate in reverse.

In another embodiment of the invention, VFD device 22 is configured as aregenerative (ReGen) drive device. A regenerative VFD is a special typeof VFD with power electronics that return power to the power grid. Sucha regenerative drive system captures any energy resulting from the fan“windmilling” and returns this energy back to the power grid.“Windmilling” occurs when the fan is not powered but is rotating inreverse due to the updraft through the cooling tower. The updraft iscaused by water in the cell. Power generated from windmilling can alsobe used to limit fan speed and prevent the fan from turning during highwinds, tornadoes and hurricanes. The regenerative VFD device is alsoconfigured to generate control signals that control motor 2004 to holdthe fan at 0.00 RPM so as to prevent windmilling in high winds orhurricanes.

Referring to FIG. 2L, the variable process control system of the presentinvention further comprises a plurality of sensors and other measurementdevices that are in electrical signal communication with DAQ device 200.Each of these sensors has a specific function. Each of these functionsis now described in detail. Referring to FIGS. 4 and 5B, the motor 2004includes vibration sensors 400 and 402 that are located within motorcasing 21. Sensor 400 is positioned on bearing housing 50 and sensor 402is positioned on bearing housing 52. Each sensor 400 and 402 isconfigured as an accelerometer, or a velocity probe or a displacementprobe. As described in the foregoing description, sensors 400 and 402are electrically connected to quick-disconnect adapter 108 and cable 110is electrically connected to quick-disconnect adapter 108 andcommunication data junction box 111. Cable 112 is electrically connectedbetween communication data junction box 111 and DAQ device 200.Vibration sensors 400 and 402 provide signals that represent vibrationsexperienced by fan 12. Vibrations caused by a particular source orcondition have a unique signature. All signals emanating from sensors400 and 402 are inputted into DAQ device 200 which processes thesesensor signals. Specifically, DAQ device 200 includes a processor thatexecutes predetermined vibration-analysis algorithms that process thesignals provided by sensors 400 and 402 to determine the signature andsource of the vibrations. Such vibration-analysis algorithms include aFFT (Fast Fourier Transform). Possible reasons for the vibrations may bean unbalanced fan 12, instability of motor 2004, deformation or damageto the fan system, resonant frequencies caused by a particular motorRPM, or instability of the fan support structure, e.g. deck. If DAQdevice 200 determines that the vibrations sensed by sensors 400 and 402are caused by a particular RPM of permanent magnet motor 2004, DAQdevice 200 generates a lock-out signal for input to VFD device 22. Thelock-out signal controls VFD device 22 to lock out the particular motorspeed (or speeds) that caused the resonant vibrations. Thus, thelock-out signals prevent motor 2004 from operating at this particularspeed (RPM). DAQ device 200 also issues signals that notify the operatorvia DCS 315. It is possible that there may be more than one resonantfrequency and in such a case, all motor speeds causing such resonantfrequencies are locked out. Thus, the motor will not operate at thespeeds (RPM) that cause these resonant frequencies. Resonant frequenciesmay change over time. However, vibration sensors 400 and 402, VFD device22 and DAQ device 200 constitute an adaptive system that adapts to thechanging resonant frequencies. The processing of the vibration signalsby DAQ device 200 may also determine that fan balancing may be requiredor that fan blades need to be re-pitched.

Fan trim balancing is performed at commissioning to identify fanimbalance, which is typically a dynamic imbalance. Static balance is thenorm. Most fans are not dynamically balanced. This imbalance causes thefan to oscillate which results in wear and tear on the tower, especiallythe bolted joints. In prior art fan drive systems, measuring fanimbalance can be performed but requires external instrumentation to beapplied to the outside of the prior art gearbox. This technique requiresentering the cell. However, unlike the prior art systems, DAQ device 200continuously receives signals outputted by vibration sensors 400 and402. Dynamic system vibration may be caused by irregular fan pitch, fanweight and or installation irregularities on the multiple fan bladesystems. Fan pitch is usually set by an inclinometer at commissioningand can change over time thereby causing fan imbalance. If the pitch ofany of the fan blades 18 deviates from a predetermined pitch orpredetermined range of pitches, then a maintenance action will beperformed on fan blades 18 in order to re-pitch or balance the blades.In a preferred embodiment, additional vibration sensors 404 and 406 arelocated on bearing housings 50 and 52, respectively, of motor 2004 (seeFIG. 4). Each vibration sensor 404 and 406 is configured as anaccelerometer or a velocity probe or a displacement probe. Eachvibration sensor 404 and 406 has a particular sensitivity and a highfidelity that is appropriate for detecting vibrations resulting from fanimbalance. Signals emanating from sensors 404 and 406 are inputted intoDAQ device 200 via cable 110, communication data junction box 111 andcable 112. Sensors 404 and 406 provide data that allows the operators toimplement correct fan trim balancing. Fan trim balancing provides adynamic balance of fan 12 that extends cooling tower life by reducing oreliminating oscillation forces or the dynamic couple that causes wearand tear on structural components caused by rotating systems that havenot been dynamically balanced. If the measured vibrations indicate fanimbalance or are considered to be in a range of serious or dangerousvibrations indicating damaged blades or impending failure, then DAQdevice 200 automatically issues an emergency stop signal to VFD device22. If the vibrations are serious, then DAQ device 200 issues controlsignals to VFD device 22 that causes motor 2004 to coast to a stop. Thefan would be held using the Fan-Hold mode of operation. Appropriate fanlocking mechanisms would be applied to the motor shaft 2006 so that thefan could be inspected and serviced. DAQ device 200 then issues alertnotifications via email or SMS text messages to the DCS 315 to informthe operators that the fan has been stopped due to serious vibrations.DAQ device 200 also issues the notification to industrial computer 300for display on display 306. If the vibration signals indicate fanimbalance but the imbalance is not of a serious nature, DAQ device 200issues a notification to the DCS 315 to alert the operators of the fanimbalance. The operators would have the option of ceasing operation ofthe cooling tower or fan cell so that the fan can be inspected andserviced if necessary. Thus, the adaptive vibration-monitoring andcompensation function of the variable process control system of thepresent invention combines with the bearing design and structure ofmotor 2004 to provide low speed, dynamic fan trim balance therebyeliminating the “vibration couple”.

It is to be understood that in alternate embodiments, one or morevibrations sensors can be mounted to the motor structure, or mounted tothe exterior of the motor, or mounted on the exterior of the motorhousing or casing, or mounted to instrumentation boxes or panels thatare attached to the exterior of the motor.

In one embodiment, a vibration sensor is mounted to the exterior ofmotor casing or housing 21 and is in data communication with DAQ device200.

The adaptive vibration feature of the variable process control systemprovides 100% monitoring, supervision and control of the direct-drivefan system with the capability to issue reports and alerts to DCS 315via e-mail and SMS that alert Operators of operating imbalances, such aspitch and fan imbalance. Large vibrations resulting from fan failure orand fan-hub failure, which typically occur within a certain vibrationspectrum, will cause DAQ device 200 to issue control signals to VFDdevice 22 to cause motor 2004 to immediately coast down to 0.0 RPM. Thefan-hold mode is then implemented. Industrial computer 300 thenimplements FFT processing of the vibration signals in order to determinethe cause of the vibrations and to facilitate prediction of impedingfailures. As part of this processing, the vibration signals are alsocompared to historic trending data in order to facilitate understandingand explanation of the cause of the vibrations.

In an alternate embodiment, the variable process control system of thepresent invention uses convenient signal pick-up connectors at severallocations outside the fan stack. These signal pick-up connectors are insignal communication with sensors 400 and 402 and can be used byoperators to manually plug in balancing equipment (e.g. Emerson CSI2130) for purposes of fan trim.

In accordance with the invention, when sensors 400, 402, 404 and 406 arefunctioning properly, the sensors output periodic status signals to DAQdevice 200 in order to inform the operators that sensors 400, 402, 404and 406 are working properly. If a sensor does not emit a status signal,DAQ device 200 outputs a sensor failure notification that is routed toDCS 315 via email or SMS text messages. The sensor failure notificationsare also displayed on display screen 306 to notify the operators of thesensor failure. Thus, as a result of the continuous 100% monitoring ofthe sensors, lost sensor signals or bad sensor signals will cause analert to be issued and displayed to the operators. This sensor failurenotification feature is a significant improvement over typical prior artsystems which require an operator to periodically inspect vibrationsensors to ensure they are working properly. This sensor failurenotification feature of the present invention significantly reduces theprobability of catastrophic fan failure. The sensors used in thevariable process control system of the present invention providebuilt-in redundancy. In a preferred embodiment, all sensors are LineReplaceable Units (LRU) that can easily be replaced. In a preferredembodiment, the Line Replaceable Units utilize area classified QuickDisconnect Adapters such as the Turck Multifast Right Angle StainlessConnector with Lokfast Guard, which was described in the foregoingdescription.

Examples of line replaceable vibration sensor units that are used todetect vibrations at motor 2004 are shown in FIGS. 18, 19 and 20.Referring to FIG. 18, there is shown a line-replaceable vibration sensorunit that is in signal communication with instrument junction box 900that is connected to motor housing or casing 21. This vibration sensorunit comprises cable gland 902 and accelerometer cable 904 which extendsacross the exterior surface of the upper portion 906 of motor casing 21.Accelerometer 908 is connected to upper portion 906 of motor casing 21.In a preferred embodiment, accelerometer 908 is connected to upperportion 906 of motor casing 21 with a Quick Disconnect Adapter such asthe Turck Multifast Right Angle Stainless Connector with Lokfast Guardwhich was described in the foregoing description. Sensor signals fromaccelerometer 908 are received by DAQ device 200 for processing. In apreferred embodiment, sensor signals from accelerometer 908 are providedto DAQ device 200 via instrument junction box 900. In such anembodiment, instrument junction box 900 is hardwired to DAQ device 200.

Another line-replaceable vibration sensor unit is shown in FIG. 19. Thisline-replaceable vibration sensor unit that is in signal communicationwith instrument junction box 900 that is connected to motor housing orcasing 21 and comprises cable gland 1002, and accelerometer cable 1004which extends across the exterior surface of the upper portion 1006 ofmotor casing 21. This vibration sensor unit further comprisesaccelerometer 1008 that is joined to upper portion 1006 of motor casing21. In a preferred embodiment, accelerometer 1008 is hermetically sealedto upper portion 1006 of motor casing 21. Sensor signals fromaccelerometer 1008 are received by DAQ device 200 for processing. In oneembodiment, sensor signals from accelerometer 1008 are provided to DAQdevice 200 via instrument junction box 900. In such an embodiment,instrument junction box 900 is hardwired to DAQ device 200.

Another line-replaceable vibration sensor unit is shown in FIG. 20. Thisline-replaceable vibration sensor unit is in signal communication withinstrument junction box 900 is connected to motor housing or casing 21and comprises cable gland 1102, and accelerometer cable 1104 whichextends across the exterior surface of the upper portion 1110 of motorcasing 21. This vibration sensor unit further comprises accelerometer1108 that is joined to upper portion 1110 of motor casing 21. In apreferred embodiment, accelerometer 1108 is hermetically sealed to upperportion 1100 of motor casing 21. Sensor signals from accelerometer 1108are received by DAQ device 200 for processing. In one embodiment, sensorsignals from accelerometer 1108 are provided to DAQ device 200 viainstrument junction box 900. In such an embodiment, instrument junctionbox 900 is hardwired to DAQ device 200.

The line-replaceable units (LRUs) described in the foregoing descriptionare powered by and networked with the internal and external electronicsand wiring of motor 2004.

Referring to FIGS. 2L and 4, the variable process control system of thepresent invention further comprises a plurality of temperature sensorsthat are positioned at different locations within the variable processcontrol system and within cooling apparatus 10. In a preferredembodiment, each temperature sensor comprises a commercially availabletemperature probe. Each temperature sensor is in electrical signalcommunication with communication data junction box 111. Temperaturesensors located within motor casing 21 are electrically connected toquick-disconnect adapter 108 which is in electrical signal communicationwith communication data junction box 111 via wires 110. The temperaturesensors that are not located within motor casing 21 are directlyhardwired to communication data junction box 111. The functions of thesesensors are as follows:

-   -   1) sensor 420 measure the temperature of the interior of motor        casing 21 (see FIG. 4);    -   2) sensors 421A and 421B measure the temperature at the motor        bearing housings 50 and 52, respectively (see FIG. 4);    -   3) sensor 422 measures the temperature of the stator 32, the end        turns, the laminations, etc. of motor 2004 (see FIG. 4);    -   4) sensor 426 is located near motor casing 21 to measure the        ambient temperature of the air surrounding motor 2004 (see FIG.        2L);    -   5) sensor 428 is located in a collection basin (not shown) of a        wet-cooling tower to measure the temperature of the water in the        collection basin (see FIG. 2L);    -   6) sensor 430 measures the temperature at DAQ device 200 (see        FIGS. 2L and 4);    -   7) sensor 432 measures the wet-bulb temperature (see FIG. 2L);    -   8) sensor 433 measures the temperature of the airflow created by        the fan (see FIGS. 2L and 4);    -   9) sensor 434 measures the external temperature of the motor        casing (see FIG. 4); and    -   10) sensor 435 detects gas leaks or other emissions (see FIG.        4).        In a preferred embodiment, there is a plurality of sensors that        perform each of the aforesaid tasks. For example, in one        embodiment, there is a plurality of sensors 428 that measure the        temperature of the water in the collection basin. Sensors 426,        428, 430, 432, 433, 434 and 435 are hard wired directly to        communication data junction box 111 and the signals provided by        these sensors are provided to DAQ device 200 via cable 112.        Since sensors 421A, 421B and 422 are within motor casing 21, the        signals from these sensors are fed to quick-disconnect adapter        108. The internal wires in motor 2004 are not shown in FIG. 2L        in order to simplify the diagram shown in FIG. 2L. A sudden rise        in the temperatures of motor casing 21 or motor stator 32 (e.g.        stator, rotor, laminations, coil, end turns, etc.) indicates a        loss of airflow and/or the cessation of water to the cell. If        such an event occurs, DAQ device 200 issues a notification to        the plant DCS 315 and also simultaneously activates alarms, such        as alarm device 438 (see FIG. 2L), and also outputs a signal to        industrial computer 300. This feature provides a safety        mechanism to prevent motor 2004 from overheating. In an        alternate embodiment, sensor 430 is not hardwired to        communication data junction box 111, but instead, is directly        wired to the appropriate input of DAQ device 200. Thus, DAQ        device 200, using the aforesaid sensors, measures the parameters        set forth in Table I:

TABLE I Parameter Measured Purpose Internal motor temperature:Monitoring, supervision, health analysis; end turns, coil lamination,detect motor overheating; detect wear or stator, internal air and damageof coil, stator, magnets; detect magnets lack of water in cell Externalmotor temperature Monitoring, supervision, health analysis; detect motoroverheating; detect lack of water in cell Bearing TemperatureMonitoring, supervision, health analysis; detect bearing wear orimpending failure; detect lubrication issues; FFT processing Fan StackTemperature Monitoring, supervision, health analysis; determine CoolingTower Thermal Capacity; determine existence of icing; operationalanalysis Plenum Pressure Monitoring, supervision, health analysis;plenum pressure equated to fan inlet pressure for mass airflowcalculation Motor Load Cells Determine fan yaw loads; system weight;assess bearing life; FFT processing Bearing Vibration Monitoring,supervision, health analysis; trim balance; adaptive vibrationmonitoring; modal testing Gas Leaks or Emissions Monitoring,supervision, health analysis; detect fugitive gas emissions; monitoringheat exchanger and condenser for gas emissions

The desired temperature of the liquid in the collection basin, alsoknown as the basin temperature set-point, can be changed by theoperators instantaneously to meet additional cooling requirements suchas cracking heavier crude, maintain vacuum backpressure in a steamturbine, prevent fouling of the heat exchanger or to derate the plant topart-load. Industrial computer 300 is in electronic signal communicationwith the plant DCS (Distributed Control System) 315 (see FIG. 2L). Theoperators use plant DCS 315 to input the revised basin temperatureset-point into industrial computer 300. Industrial computer 300communicates this information to DAQ device 200. Sensor 428 continuouslymeasures the temperature of the liquid in the collection basin in orderto determine if the measured temperature is above or below the basintemperature set-point. DAQ device 200 processes the temperature dataprovided by sensor 428, the revised basin temperature set point, thecurrent weather conditions, thermal and process load, and pertinenthistorical data corresponding to weather, time of year and time of day.

In one embodiment, wet-bulb temperature is measured with suitableinstrumentation such as psychrometers, thermohygrometers or hygrometerswhich are known in the art.

As a result of the adaptive characteristics of the variable processcontrol system of the present invention, a constant basin temperature ismaintained despite changes in process load, Cooling Tower ThermalCapacity, weather conditions or time of day. DAQ device 200 continuouslygenerates an updated sinusoidal fan speed curve in response to thechanging process load, Cooling Tower Thermal Capacity, weatherconditions or time of day.

Temperature sensor 430 measures the temperature at DAQ device 200 inorder to detect overheating cause by electrical overload, short circuitsor electronic component failure. In a preferred embodiment, ifoverheating occurs at DAQ device 200, then DAQ device 200 issues anemergency stop signal to VFD device 22 to initiate an emergency “SoftStop Mode” to decelerate motor 2004 to 0.00 RPM and to activate alarms(e.g. alarm 438, audio alarm, buzzer, siren, horn, flashing light, emailand text messages to DCS 315, etc.) to alert operators to the fact thatthe system is attempting an emergency shut-down procedure due toexcessive temperatures. In one embodiment of the present invention, ifoverheating occurs at DAQ device 200, DAQ device 200 issues a signal toVFD device 22 to maintain the speed of motor 2004 at the current speeduntil the instrumentation can be inspected.

The operating parameters of motor 2004 and the cooling tower areprogrammed into DAQ device 200. DAQ device 200 comprises amicroprocessor or mini-computer and has computer processing power. Manyof the operating parameters are defined over time and are based on theoperating tolerances of the system components, fan and tower structure.Problems in the cooling tower such as clogged fill, poor waterdistribution, etc. can cause gradual heating of motor 2004 and/or itsinternal components in small increments. Such internal componentsinclude the motor's stator, rotor, laminations, coil, end turns, etc.Such problems can be determined by trending cooling tower operationaldata over a period of time (e.g. weeks or months) and comparing suchtrends with variations in horsepower (i.e. reduced horsepower) or fantorque over the same time interval. Industrial computer 300 will processthe data to extrapolate any trends and then compare the trends toprevious trends and data. This processing will enable industrialcomputer 300 to determine whether to display a notice or alert ondisplay 306 that an inspection of the cooling tower is necessary. Asudden rise in motor temperature as a function of time may indicate thatthe cell water has been shut-off. Such a scenario will trigger aninspection of the tower. The variable process control system of thepresent invention is designed to notify operators of any deviation fromoperating parameters. When deviations from these operating parametersand tolerances occur relative to time, DAQ device 200 issues signals tothe operators in order to notify them of the conditions and that aninspection is necessary. Relative large deviations from the operatingparameters, such as a large vibration spike or very high motortemperature, would cause DAQ device 200 to generate a control signal toVFD device 22 that will enable motor 2004 to coast to complete stop. Thefan is then held at 0.0 RPM via the Fan Hold mode of operation. DAQdevice 200 simultaneously issues alerts and notifications via emailand/or text messages to DCS 315.

As described in the foregoing description, VFD device 22, DAQ device 200and industrial computer 300 are housed in Motor Control Enclosure (MCE)26. The variable process control system includes a purge system thatmaintains a continuous positive pressure on cabinet 26 in order toprevent potentially explosive gases from being drawn into MCE 26. Suchgases may originate from the heat exchanger. The purge system comprisesa compressed air source and a device (e.g. hose) for delivering acontinuous source of pressurized air to MCE 26 in order to create apositive pressure which prevents entry of such explosive gases. In analternate embodiment, MCE 26 is cooled with Vortex coolers that utilizecompressed air. In a further embodiment, area classified airconditioners are used to deliver airflow to MCE 26.

Referring to FIG. 2L, in a preferred embodiment, the system of thepresent invention further includes at least one pressure measurementdevice 440 that is located on the fan deck and which measures thepressure in the cooling tower plenum. In a preferred embodiment, thereis a plurality of pressure measurement devices 400 to measure thepressure in the cooling tower plenum. Each pressure measurement device440 is electrically connected to communication data junction box 111.The measured pressure equates to the pressure before the fan (i.e. faninlet pressure). The measured pressure is used to derive fan pressurefor use in cooling performance analysis.

It is critical that the fan be located at the correct fan height inorder to produce the requisite amount of design fan pressure. The fanmust operate at the narrow part of the fan stack in order to operatecorrectly, as shown in FIG. 13. Many prior art fan drive systems do notmaintain the correct fan height within the existing parabolic fan stackinstallation. Such a misalignment in height causes significantdegradation in cooling capacity and efficiency. An important feature ofthe direct-drive system of the present invention is that the designarchitecture of motor 2004 maintains or corrects the fan height in thefan stack. Referring to FIGS. 13 and 14, there is shown a diagram of awet cooling tower that uses the direct-drive system of the presentinvention. The wet cooling tower comprises fan stack 14 and fan deck250. Fan stack 14 is supported by fan deck 250. Fan stack 14 has agenerally parabolic shape. In other embodiments, fan stack 14 can have astraight cylinder shape (i.e. cylindrical shape). Fan stack 14 and fandeck 250 were discussed in the foregoing description. In a parabolic fanstack 14, the height of the motor must correctly position the fan at thecorrect height within the narrow throat section of fan stack 14 in orderto seal the end of the fan blade at the narrow throat section of the fanstack 14. Positioning the fan at the correct height assures that the fanwill operate correctly and efficiently and provide the proper fan pumphead for the application. Referring to FIG. 13, the wet cooling towerincludes fan assembly 12 which was described in the foregoingdescription. The height H indicates the correct height at which the fanblades 18 must be located within fan stack 14. This correct height isthe uppermost point of the narrow throat section of the fan stack 14. Anoptional adapter plate (not shown) can be used to accurately positionthe fan blades 18 at the correct height H (see FIG. 13). Retrofittingmotor 2004 and correcting fan height can actually increase airflowthrough the cooling tower by setting the fan assembly 12 at the correctheight H. The optional adapter plate (not shown) can be positionedbetween the ladder frame/torque tube (not shown) and motor 2004 suchthat motor 2004 is seated upon and connected to the adapter plate.Direct-drive system 2000 is connected to a ladder frame or torque tubeor other suitable metal frame that extends over the central opening inthe fan deck 250. In one embodiment, direct-drive system 2000 isdesigned such that only four bolts are needed to connect direct-drivesystem 2000 to the existing ladder frame or torque tube. As shown inFIG. 12B, the overall housing of direct-drive system 2000 has four holes264A, 264B, 264C and 264D extending therethrough to receive fourmounting bolts. If an optional adapter plate (not shown) is used, theadapter plate is designed with corresponding through-holes that receivethe aforementioned four bolts. The four bolts extend through thecorresponding openings 264A, 264B, 264C and 264D and through thecorresponding openings in the adapter plate and also extend throughcorresponding openings in the ladder frame or torque tube. Thus, bydesign, the architecture of direct-drive system 2000 is designed to be adrop-in replacement for all prior art gearboxes (see FIG. 1) andmaintains or corrects fan height in the fan stack 14 without structuralmodifications to the cooling tower or existing ladder frame or torquetubes. Such a feature and advantage is possible because direct-drivesystem 2000 is designed to have a weight that is the same or less thanthe prior art gearbox system it replaces. The mounting configuration ofdirect-drive system 2000 (see FIG. 12B) allows direct-drive system 2000to be mounted to existing interfaces on existing structural ladderframes and torque tubes and operate within the fan stack meeting AreaClassification for Class 1, Div. 2, Groups B, C, D. Therefore, new oradditional ladder frames and torque tubes are not required whenreplacing a prior art gearbox system with direct-drive system 2000.Since direct-drive system 2000 has a weight that is the same or lessthan the prior art gearbox it replaces, direct-drive system 2000maintains the same weight distribution on the existing ladder frame ortorque tube. Direct-drive system 2000 is connected to fan hub 16 in thesame way as a prior art gearbox is connected to fan hub 16. The onlycomponents needed to install direct-drive system 2000 are: (a)direct-drive system 2000 having power cable 105 wired thereto asdescribed in the foregoing description, wherein the other end of powercable 105 is adapted to be electrically connected to motor disconnectjunction box 106, (b) the four bolts that are inserted intothrough-holes 264A, 264B, 264C and 264D in the housing of direct-drivesystem 2000, (c) cable 110 having one terminated at a quick-disconnectadapter 108, and the other end adapted to be electrically connected tocommunication data junction box 111 (d) power cable 107 which is adaptedto be electrically connected to motor disconnect junction box 106, and(e) VFD device 22. As a result of the design of direct-drive system2000, the process of replacing a prior art drive system withdirect-drive system 200 is simple, expedient, requires relatively lesscrane hours, and requires relatively less skilled labor than required toinstall and align the complex, prior art gearboxes, shafts andcouplings. In a preferred embodiment, direct-drive system 2000 includeslifting lugs or hooks 270 that are rigidly connected to or integrallyformed with the housing of drive-drive system 2000. These lifting lugs270 are located at predetermined locations on the housing ofdrive-system 2000 so that direct-drive system 2000 is balanced whenbeing lifted by a crane during the installation process. Direct-drivesystem 2000 and its mounting interfaces have been specifically designedfor Thrust, Pitch, Yaw, reverse loads and fan weight (i.e. dead load).

Thus, direct-drive system 2000 is specifically designed to fit withinthe installation envelope of an existing, prior art gearbox and maintainor correct the fan height in the fan stack. In one embodiment, theweight of direct-drive system 2000 is less than or equal to the weightof the currently-used motor-shaft-gearbox drive system. In a preferredembodiment of the invention, the weight of direct-drive system 2000 doesnot exceed 2500 lbs. In one embodiment, direct-drive system 2000 has aweight of approximately 2350 lbs. Direct-drive system 2000 has beenspecifically designed to match existing interfaces with fan-hub shaftdiameter size, profile and keyway. Direct-drive system 2000 can rotateall hubs and attaching fans regardless of direction, blade length, fansolidity, blade profile, blade dimension, blade pitch, blade torque, andfan speed.

It is to be understood that direct-drive system 2000 may be used withother models or types of cooling tower fans. For example, direct-drivesystem 2000 may be used with any of the commercially available 4000Series Tuft-Lite Fans manufactured by Hudson Products, Corporation ofHouston, Tex. In an alternate embodiment, direct-drive system 2000 isconnected to a fan that is configured without a hub structure. Such fansare known are whisper-quiet fans or single-piece wide chord fans. Whensingle-piece wide chord fans are used, rotatable output shaft 2010 ofdirect-drive system 2000 is directly bolted or connected to the fan. Onecommercially available whisper-quiet fan is the PT2 Cooling TowerWhisper Quiet Fan manufactured by Baltimore Aircoil Company of Jessup,Md. Furthermore, all of the embodiments of the load bearing direct-drivesystem of the present invention may be used with any type of fan,centrifugal fan, axial fan, impeller and propeller that can move air orgasses. Additionally, all of the embodiments of the load bearingdirect-drive system of the present invention may be used with any typeof pump that move and/or pressurize liquids and/or gasses. For example,all of the embodiments of the direct-drive system of the presentinvention may be used with the low noise, high efficiency fans, axialfans, centrifugal fans, impellers and propellers designed by TurboMoniApplied Dynamics Lab of Ottawa, Ontario, Canada.

Direct-drive system 2000 is designed to withstand the harsh chemicalattack, poor water quality, mineral deposits, pH attack, biologicalgrowth and humid environment without contaminating the lubricationsystem or degrading the integrity of direct-drive system 2000.Direct-drive system 2000 operates within the fan stack and does notrequire additional cooling ducts or flow scoops.

For a new installation (i.e. newly constructed cooling tower), theinstallation of direct-drive system 2000 does not require ladder framesand torque tubes as do typical prior art gearbox systems. Theelimination of ladder frames and torque tubes provides a simplerstructure at a reduced installation costs. The elimination of the ladderframe and torque tubes significantly reduces obstruction and blockagefrom the support structure thereby reducing airflow loss. Theelimination of ladder frames and torque tubes also reduce fan pressureloss and turbulence. The installation of direct-drive system 2000therefore is greatly simplified and eliminates multiple components,tedious alignments, and also reduces installation time, manpower and thelevel of skill of the personnel installing direct-drive system 2000. Theelectrical power is simply connected at motor junction box 106. Thepresent invention eliminates shaft penetration through the fan stackthereby improving fan performance by reducing airflow loss and fanpressure loss.

Cable 105 is terminated or prewired at direct-drive system 2000 duringthe assembly of direct-drive system 2000. Such a configurationsimplifies the installation of direct-drive system 2000. Otherwise,confined-space entry training and permits would be required for anelectrician to enter the cell to install cable 105 to direct-drivesystem 2000. Furthermore, terminating cable 105 to direct-drive system2000 during the manufacturing process provides improved reliability andsealing of direct-drive system 2000 since the cable 105 is assembled andterminated at direct-drive system 2000 under clean conditions, withproper lighting and under process and quality control. If direct-drivesystem 2000 is configured as a three-phase motor, then cable 105 iscomprised of three wires and these three wires are to be connected tothe internal wiring within motor disconnect junction box 106.

The smooth operation of direct-drive system 2000 and its drive systemallows accurate control, supervision, monitoring and system-healthmanagement because the variable process control system of the presentinvention is more robust. On the other hand, prior art gear-train meshes(i.e. motor, shaft, couplings and subsequent multiple gear-trainsignatures) have multiple vibration signatures and resultantcross-frequency noise that are difficult to identify and manageeffectively. Direct-drive system 2000 increases airflow through acooling tower by converting more of the applied electrical energy intoairflow because it eliminates the losses of the prior art gearboxsystems and is significantly more efficient than the prior art gearboxsystems.

A common prior art technique employed by many operators of coolingtowers is to increase water flow into the cooling towers in order toimprove condenser performance. FIG. 17 shows a graph of approximatedcondenser performance. However, the added stress of the increased waterflow causes damage to the cooling tower components and actually reducescooling performance of the tower (L/G ratio). In some cases, it can leadto catastrophic failure such as the collapse of the cooling tower.However, with the variable process control system of the presentinvention, increasing water flow is totally unnecessary because thecooling tower design parameters are programmed into both DAQ device 200and industrial computer 300. Specifically, in the variable processcontrol system of the present invention, the cooling tower pumps andauxiliary systems are networked with the fans to provide additionalcontrol, supervision and monitoring to prevent flooding of the tower anddangerous off-performance operation. In such an embodiment, the pumpsare hardwired to DAQ device 200 so that DAQ device 200 controls theoperation of the fan, motor and pumps. In such an embodiment, pump-watervolume is monitored as a way to prevent the collapse of the tower underthe weight of the water. Such monitoring and operation of the pumps willimprove part-load cooling performance of the tower as the L/G ratio ismaximized for all load and environmental conditions. Such monitoring andoperation will also prevent flooding and further reduce energyconsumption. The flow rate through the pumps is a function of processdemand or the process of a component, such as the condenser process. Ina preferred embodiment, the variable process control system of thepresent invention uses variable speed pumps. In an alternate embodiment,variable frequency drive devices, similar to VFD device 22, are used tocontrol the variable speed pumps in order to further improve part-loadperformance. In a further embodiment, the cooling tower variable speedpumps are driven by permanent magnet motors that have the same orsimilar characteristics as direct-drive system 2000.

Thus, the present invention can:

-   -   1) operate the fan at a constant speed;    -   2) vary the speed of the fan to maintain a constant basin        temperature as the environmental and process demand conditions        change;    -   3) use current wet-bulb temperature and environmental stress and        past process demand and past environmental stress to anticipate        changes in fan speed, and ramp fan speed up or ramp fan speed        down in accordance with a sine wave (see FIG. 9) in order to        meet cooling demand and save energy with relatively smaller and        less frequent changes in fan speed;    -   4) vary the speed of the fan to maintain a constant basin        temperature as environmental stress and process demands change        AND maintain pre-defined heat exchanger and turbine        back-pressure set-points in the industrial process in order to        maintain turbine back-pressure and avoid heat exchanger fouling;    -   5) vary the speed of the fan and the speed of the variable speed        pumps to maintain a constant basin temperature as environmental        stress and process demands change AND maintain pre-defined heat        exchanger and turbine back-pressure set-points in the industrial        process in order to maintain turbine back-pressure and avoid        heat exchanger fouling;    -   6) vary the speed of the fan to maintain a constant basin        temperature as environmental stress and process conditions        change AND maintain pre-defined heat exchanger and turbine        back-pressure set-points in the industrial process in order to        maintain turbine back-pressure and avoid heat exchanger fouling        AND prevent freezing of the cooling tower by either reducing fan        speed or operating the fan in reverse;    -   7) vary the speed of the fan to change basin temperature as        environmental stress and process conditions change AND maintain        pre-defined heat exchanger and turbine back-pressure set-points        in the industrial process in order to maintain turbine        back-pressure and avoid heat exchanger fouling AND prevent        freezing of the cooling tower by either reducing fan speed or        operating the fan in reverse; and    -   8) vary the speed of the fan and the speed of the variable speed        pumps to change the basin temperature as environmental stress        and process conditions change AND maintain turbine back-pressure        and avoid heat exchanger fouling AND prevent freezing of the        cooling tower by either reducing fan speed or operating the fan        in reverse.

Referring to FIG. 26, there is shown a schematic diagram of the variableprocess control system and direct-drive system 2000 of the presentinvention used with a wet-cooling tower that is part of an industrialprocess. In this embodiment, the variable process control systemincludes a plurality of variable speed pumps. Each variable speed pumpcomprises direct-drive system 2000 wherein motor 2004 is a permanentmagnet motor and torque multiplier device 2002 is an epicyclic tractiondevice. In this embodiment, the aforesaid permanent magnet motor isconfigured as the permanent magnet motor shown in FIGS. 5A and 5B.However, it is to be understood that the direct-drive system for drivingthe fan and the pumps may be configured as any of the direct-drivesystems shown in FIGS. 2A-2J. As shown in FIG. 26, wet-cooling tower1700 comprises tower structure 1702, fan deck 1704, fan stack 1706 andcollection basin 1708. Cooling tower 1700 includes fan 1710 anddirect-drive system 2000 which drives fan 1710. Fan 1710 has the samestructure and function as fan 12 which was described in the foregoingdescription. Cooling tower 1700 includes an inlet for receiving make-upwater 1712. The portion of cooling tower 1700 that contains the fillmaterial, which is well known in the art, is not shown in FIG. 26 inorder to simplify the drawing. Collection basin 1708 collects watercooled by fan 1710. Variable speed pumps pump the cooled water fromcollection basin 1708, to condenser 1714, and then to process 1716wherein the cooled water is used in an industrial process. It is to beunderstood that condenser 1714 is being used as an example and a similardevice, such as a heat exchanger, can be used as well. The condensertemperature set-point is typically set by the operators through theDistributed Control System 315 (see FIG. 3) via signal 1717. Theindustrial process may be petroleum refining, turbine operation, crudecracker, etc. The variable speed pumps also pump the heated water fromprocess 1716 back to condenser 1714 and then back to cooling tower 1700wherein the heated water is cooled by the operation of the cooling tower1700. Cooled water exiting collection basin 1708 is pumped by variablespeed pump 1722 to condenser 1714. Variable speed pump 1722 furtherincludes an instrumentation module which outputs pump status datasignals 1726 that represent the flow rate, pressure and temperature ofwater flowing through variable speed pump 1722 and into condenser 1714.Data signals 1726 are inputted into DAQ device 200. This feature will bediscussed in the ensuing description. Water exiting condenser 1714 ispumped to process 1716 by variable speed pump 1730. Variable speed pump1730 includes an instrumentation module that outputs pump status datasignals 1734 that represent the flow rate, pressure and temperature ofwater flowing through variable speed pump 1730. Water leaving process1716 is pumped back to condenser by 1714 by variable speed pump 1738.Variable speed pump 1738 includes an instrumentation module whichoutputs pump status data signals 1742 that represent the flow rate,pressure and temperature of water flowing through variable speed pump1738. The water exiting condenser 1714 is pumped back to cooling tower1700 by variable speed pump 1752. Variable speed pump 1752 furtherincludes an instrumentation module that outputs pump status data signals1756 that represent the flow rate, pressure and temperature of waterflowing through variable speed pump 1752.

VFD device 22 comprises a plurality of Variable Frequency Devices.Specifically, VFD device 22 comprises VFD devices 23A, 23B, 23C, 23D and23E. VFD device 23A outputs power over power cable 107. Power cables 107and 105 are connected to junction box 106. Power cable 105 delivers thepower signals to motor 2004. Power cables 105 and 107 and junction box106 were discussed in the foregoing description. VFD device 23B outputspower signal 1724 for controlling the permanent magnet motor of thedirect-drive system in variable speed pump 1722. VFD device 23C outputspower signal 1732 for controlling the permanent magnet motor of thedirect-drive system in the variable speed pump 1730. VFD device 23Doutputs power signal 1740 for controlling the permanent magnet motor ofthe direct-drive system in variable speed pump 1738. VFD device 23Eoutputs power signal 1754 for controlling the permanent magnet motor ofthe direct-drive system in variable speed pump 1752. DAQ device 200 isin electronic signal communication with VFD devices 23A, 23B, 23C, 23Dand 23E. DAQ device 200 is programmed to control each VFD device 23A,23B, 23C, 23D and 23E individually and independently. All variable speedpump output data signals 1726, 1734, 1742 and 1756 from the variablespeed pumps 1722, 1730, 1738 and 1752, respectively, are inputted intoDAQ device 200. DAQ device 200 processes these signals to determine theprocess load and thermal load. DAQ device 200 determines the thermalload by calculating the differences between the temperature of the waterleaving the collection basin and the temperature of the water returningto the cooling tower. DAQ device 200 determines process demand byprocessing the flow-rates and pressure at the variable speed pumps. OnceDAQ device 200 determines the thermal load and process load, itdetermines whether the rotational speed of the fan 1710 is sufficient tomeet the process load. If the current rotational speed of the fan is notsufficient, DAQ device 200 develops a fan speed curve that will meet thethermal demand and process demand. As described in the foregoingdescription, DAQ device 200 uses Cooling Tower Thermal Capacity, currentthermal demand, current process demand, current environmental stress,and historical data, such as historic process and thermal demand andhistoric environmental stress to generate a fan speed curve.

As shown in FIG. 26, DAQ device 200 also receives the temperature andvibration sensor signals that were discussed in the foregoingdescription. Typically, the basin temperature set-point is based on thecondenser temperature set-point which is usually set by the plantoperators. DAQ device 200 determines if the collection basin temperaturemeets the basin temperature set-point. If the collection basintemperature is above or below the basin temperature set-point, then DAQdevice 200 adjusts the rotational speed of motor 2004 in accordance witha revised or updated fan speed curve. Therefore, DAQ device 200processes all sensor signals and data signals from variable speed pumps1722, 1730, 1738 and 1752. DAQ device 200 is programmed to utilize theprocessed signals to determine if the speed of the variable speed pumpsshould be adjusted in order to increase cooling capacity for increasedprocess load, adjust the flow rate of water into the tower, preventcondenser fouling, maintain vacuum back-pressure, or adjust theflow-rate and pressure at the pumps for plant-part load conditions inorder to conserve energy. If speed adjustment of the variable speedpumps is required, DAQ device 200 generates control signals that arerouted over data bus 202 for input to VFD devices 23B, 23C, 23D and 23E.In response, these VFD devices 23B, 23C, 23D and 23E generate powersignals 1724, 1732, 1740 and 1754, respectively, for controlling thepermanent magnet motors of the direct-drive systems in variable speedpumps 1722, 1730, 1738 and 1752, respectively. DAQ device 200 controlseach VFD device 23A, 23B, 23C, 23D and 23E independently. Thus, DAQdevice 200 can increase the speed of one variable speed pump whilesimultaneously decreasing the speed of another variable speed pump andadjusting the speed of the fan 1710.

In an alternate embodiment of the invention, all variable speed pumpoutput data signals 1726, 1734, 1742 and 1756 are not inputted into DAQdevice 200 but instead, are inputted into industrial computer 300 (seeFIG. 3) which processes the pump output data signals and then outputspump control signals directly to the VFD devices 23B, 23C, 23D and 23E.

Each instrumentation module of each variable speed pump includes sensorsfor measuring motor and pump vibrations and temperatures. The signalsoutputted by these sensors are inputted to DAQ device 200 forprocessing.

It is to be understood that instrumentation of than the aforesaidinstrumentation modules may be used to provide the pump status signals.The electrical power source for powering all electrical components andinstruments shown in FIG. 26 is not shown in order to simplify thedrawing. Furthermore, all power and signal junction boxes are not shownin order to simplify the drawing.

DAQ device 200 and industrial computer 300 allow monitoring of theCooling Tower Thermal Capacity, energy consumption and cooling toweroperation thereby allowing management of energy, enhancement of coolingtower performance and efficient and accurate trouble shooting.

In an alternate embodiment, a single VFD device is used to drive morethan one motor. For example, a single VFD device can be used to driveall of the pump motors.

It is to be understood that any pump that is used to pump fluid or gas,create flow in a fluid or gas, or pressurize a fluid or gas, mayincorporate any of the embodiments of the load bearing, direct drivesystem of the present invention and provide shaft rotation and torquewhile absorbing external loads that require additional bearing, sealsand structure to handle the increased loading beyond that of motorforces.

The Federal Clean Air Act and subsequent legislation will requiremonitoring of emissions from cooling towers of all types (Wet Cooling,Air and HVAC). Air and hazardous gas monitors can be integrated into themotor housing 21 as Line Replaceable Units to sense leaks in the system.The Line Replaceable Units (LRU) are mounted and sealed into the motorin a manner similar to the (LRU) vibration sensors described in theforegoing description. The LRUs will use power and data communicationresources available to other components of the variable process controlsystem. Hazardous gas monitors can also be located at various locationsin the cooling tower fan stack and air-flow stream. Such monitors can beelectronically integrated with DAQ device 200. The monitors provideimproved safety with 100% monitoring of dangerous gases and also providethe capability to trace the source of the gas (e.g. leaking condenser,heat exchanger, etc.). Such a feature can prevent catastrophic events.

In response to the data provided by the sensors, DAQ device 200generates appropriate signals to control operation of motor 2004 andhence direct-drive system 2000. Thus, the variable process controlsystem of the present invention employs feedback control of motor 2004and monitors all operation and performance data in real-time. As aresult, the operation of direct-drive system 2000 and fan assembly 12will vary in response to changes in operating conditions, processdemand, environmental conditions and the condition of subsystemcomponents. The continuous monitoring feature provide by the feedbackloops of the variable process control system of the present invention,shown in FIG. 3, is critical to efficient operation of the cooling towerand the prevention of failure of and damage to the cooling tower and thecomponents of the system of the present invention. As a result ofcontinuously monitoring the parameters of motor 2004 that directlyrelate to the tower airflow, operating relationships can be determinedand monitored for each particular cooling tower design in order tomonitor motor health, cooling tower health, Cooling Tower ThermalCapacity, provide supervision, trigger inspections and triggermaintenance actions. For example, in the system of the presentinvention, the horsepower (HP) of motor 2004 is related to airflowacross fan 12. Thus, if the fill material of the tower is clogged, theairflow will be reduced. This means that motor 2004 and fan assembly 12must operate longer and under greater strain in order to attain thedesired basin temperature. The temperature within the interior of motorcasing 21 and stator 32 increases and the motor RPM starts to decrease.The aforementioned sensors measure all of these operating conditions andprovide DAQ device 200 with data that represents these operatingconditions. The feedback loops continuously monitor system resonantvibrations that occur and vary over time and initiate operationalchanges in response to the resonant vibrations thereby providingadaptive vibration control. If resonant vibrations occur at a certainmotor speed, then the feedback loops cause that particular motor speed(i.e. RPM) to be locked out. When a motor speed is locked out, it meansthat the motor 20 will not be operated at that particular speed. If thevibration signature is relatively high, which may indicate changes inthe fan blade structure, ice build-up or a potential catastrophic bladefailure, the feedback loops will cause the system to shut down (i.e.shut direct-drive system 2000). If a vibration signature corresponds tostored data representing icing conditions (i.e. temperature, wind andfan speed), then DAQ device 200 will automatically initiate the De-IcingMode of operation. Thus, the feedback loops, sensors, pump statussignals, and DAQ device 200 cooperate to:

-   -   a) measure vibrations of the bearings of motor 2004;    -   b) measure temperature of the stator of motor 2004;    -   c) measure temperature within motor casing 21;    -   d) measure environmental temperatures near motor 2004 and fan        assembly 12;    -   e) determine process demand;    -   f) measure the temperature of the water in the cooling tower        collection basin;    -   g) identify high vibrations which are the characteristics of        “blade-out” or equivalent and immediately decelerate the fan to        zero (0) RPM and hold the fan from windmilling, and immediately        alert the operators using notifications and alert systems (e.g.        email, text or DCS alert);    -   h) lock out particular motor speed (or speeds) that create        resonance;    -   i) identify icing conditions and automatically initiate the        De-Icing Mode of operation and alert operators and personnel via        e-mail, text or DCS alert; and    -   j) route the basin-water temperature data to other portions of        the industrial process so as to provide real-time cooling        feedback information that can be used to make other adjustments        in the overall industrial process.

In a preferred embodiment, the variable process control system of thepresent invention further comprises at least one on-sight camera 480that is located at a predetermined location. Camera 480 is in electricalsignal communication with communication data junction box 111 andoutputs a video signal that is fed to DAQ device 200. The video signalsare then routed to display screens that are being monitored byoperations personnel. In a preferred embodiment, the video signals arerouted to industrial computer 300 and host server 310. The on-sightcamera 480 monitors certain locations of the cooling tower to ensureauthorized operation. For example, the camera can be positioned tomonitor direct-drive system 2000, the cooling tower, the fan, etc. forunauthorized entry of persons, deformation of or damage to systemcomponents, or to confirm certain conditions such as icing. In apreferred embodiment, there is a plurality of on-sight cameras.

Industrial computer 300 is in data communication with data base 301 forstoring (1) historical data, (2) operational characteristics ofsubsystems and components, and (3) actual, real-time performance andenvironmental data. Industrial computer 300 is programmed to use thisdata to optimize energy utilization by direct-drive system 2000 andother system components, generate trends, predict performance, predictmaintenance, and monitor the operational costs and efficiency of thesystem of the present invention. Industrial computer 300 uses historicaldata, as a function of date and time, wherein such historical dataincludes but is not limited to (1) weather data such as dry bulbtemperature, wet bulb temperature, wind speed and direction, andbarometric temperature, (2) cooling tower water inlet temperature fromthe process (e.g. cracking crude), (3) cooling tower water outlettemperature return to process, (4) fan speed, (5) cooling tower plenumpressure at fan inlet, (6) vibrations of motor bearings, (7) all motortemperatures, (8) cooling tower water flow rate and pump flow-rates, (9)basin temperature, (10) process demand for particular months, seasonsand times of day, (11) variations in process demand for differentproducts, e.g. light crude, heavy crude, etc., (12) previous maintenanceevents, and (13) library of vibration signatures, (14) cooling towerdesign, (15) fan map, (16) fan pitch and (17) Cooling Tower ThermalCapacity.

Industrial computer 300 also stores the operational characteristics ofsubsystems or components which include (1) fan pitch and balancing atcommissioning, (2) known motor characteristics at commissioning such ascurrent, voltage and RPM ratings, typical performance curves, andeffects of temperature variations on motor performance, (3) variation inperformance of components or subsystem over time or between maintenanceevents, (4) known operating characteristics of variable frequency drive(VFD), (5) operating characteristics of accelerometers includingaccuracy and performance over temperature range, and (6) cooling towerperformance curves and (7) fan speed curve. Actual real-time performanceand environmental data are measured by the sensors of the system of thepresent invention and include:

-   -   1) weather, temperature, humidity, wind speed and wind        direction;    -   2) temperature readings of motor interior, motor casing, basin        liquids, air flow generated by fan, variable frequency drive,        and data acquisition device;    -   3) motor bearing accelerometer output signals representing        particular vibrations (to determine fan pitch, fan balance and        fan integrity);    -   4) plenum pressure at fan inlet;    -   5) pump flow-rates which indicate real-time variations in        process demand;    -   6) motor current (amp) draw and motor voltage;    -   7) motor RPM (fan speed);    -   8) motor torque (fan torque);    -   9) motor power factor;    -   10) motor horsepower, motor power consumption and efficiency;    -   11) exception reporting (trips and alarms);    -   12) system energy consumption; and    -   13) instrumentation health.

Industrial computer 300 processes the actual real-time performance andenvironmental data and then correlates such data to the storedhistorical data and the data representing the operationalcharacteristics of subsystems and components in order to perform thefollowing tasks: (1) recognize new performance trends, (2) determinedeviation from previous trends and design curves and related operatingtolerance band, (3) determine system power consumption and relatedenergy expense, (4) determine system efficiency, (5) development ofproactive and predictive maintenance events, (6) provide information asto how maintenance intervals can be maximized, (7) generate new fanspeed curves for particular scenarios, and (8) highlight areas whereinmanagement and operation can be improved. VFD device 22 provides DAQdevice 200 with data signals representing motor speed, motor current,motor torque, and power factor. DAQ device 200 provides this data toindustrial computer 300. As described in the foregoing description,industrial computer 300 is programmed with design fan map data andcooling tower thermal design data. Thus, for a given thermal load(temperature of water in from process, temperature of water out fromprocess and flow, etc.) and a given day (dry bulb temp, wet bulb temp,barometric pressure, wind speed and direction, etc.), the presentinvention predicts design fan speed from the tower performance curve andthe fan map and then compares the design fan speed to operatingperformance. The design of each tower is unique and therefore theprogramming of each tower is unique. The programmed operation of alltowers includes the cooling tower historical trend data showing that aclogged tower causes the motor to operate for longer periods of time andat a higher speed (RPM). Such increased duration of motor operation andmotor speed would be monitored and recorded and then used to formulatetrend data which would then be compared to the pre-stored and/or knowncooling tower operation trend data. Fan inlet pressure sensors are inelectronic signal communication with DAQ device 200 and provide datarepresenting airflow. Since industrial computer 300 determines operatingtolerances based on trending data, the operation of the fan 12 at higherspeeds may trigger an inspection.

Industrial computer 300 is programmed to compare the signals of thevibration sensors 400, 402, 404 and 406 on motor the bearing housings 50and 52 as a way to filter environmental noise. In a preferredembodiment, industrial computer 300 is programmed so that certainvibration frequencies are maintained or held for a predetermined amountof time before any reactive measures are taken. Certain vibrationfrequencies indicate different failure modes and require a correspondingreaction measure. The consistent and tight banding of the vibrationsignature of direct-drive system 2000 allows for greater control andsupervision because changes in the system of the present invention canbe isolated and analyzed immediately thereby allowing for correctiveaction. Isolated vibration spikes in the system of the present inventioncan be analyzed instantaneously for amplitude, duration, etc. Opposingmotor bearing signatures can be compared to minimize and eliminatesystem trips due to environmental vibrations without impacting safetyand operation (false trip). As described in the foregoing description,industrial computer 300 is also programmed with operationalcharacteristics of the wet-cooling tower and ACHE. For example,industrial computer 300 has data stored therein which represents theaerodynamic characteristics of the fill material in the cooling tower.The processor of industrial computer 300 implements algorithms thatgenerate compensation factors based on these aerodynamiccharacteristics. These compensation factors are programmed into theoperation software for each particular cooling tower. Thus, the positiveor negative aerodynamic characteristics of the fill material of aparticular wet-cooling tower or ACHE are used in programming theoperation of each wet-cooling tower or ACHE. As described in theforegoing description, industrial computer 300 is programmed with thehistorical weather data for the particular geographical location inwhich the wet-cooling tower or ACHE is located. Industrial computer 300is also programmed with historical demand trend which providesinformation that is used in predicting high-process demand andlow-process demand periods. Since industrial computer 300 and DAQ device200 are programmed with the cooling tower thermal design data that isunique to each tower including the fan map, each cooling tower can bedesigned to have its own unique set of logic depending on itsgeographical location, design (e.g. counter-flow, cross flow, ACHE,HVAC) and service (e.g. power plant, refinery, commercial cooling,etc.). When these characteristics are programmed into industrialcomputer 300, these characteristics are combined with sufficientoperational data and trending data to establish an operational curvetolerance band for that particular cooling tower. This enables coolingtower operators to predict demand based upon historical operationalcharacteristics and optimize the fan for energy savings by using subtlespeed changes as opposed to dramatic speed changes to save energy.

A significant feature of the present invention is that the air flowthrough the cooling tower is controlled via the variable speed fan tomeet thermal demand and optimize energy efficiency of the system. DAQdevice 200 generates motor-speed control signals that are based onseveral factors including cooling tower basin temperature, historicaltrending of weather conditions, process cooling demand, time of day,current weather conditions such as temperature and relative humidity,cooling tower velocity requirements, prevention of icing of the tower byreducing fan speed, and de-icing of the tower using reverse rotation ofthe fan. Thus, the system of the present invention can anticipatecooling demand and schedule the fan (or fans) to optimize energy savings(ramp up or ramp down) while meeting thermal demand. The system of thepresent invention is adaptive and thus learns the cooling demand byhistorical trending (as a function of date and time).

The speed of the fan or fans may be increased or decreased as a resultof any one of several factors. For example, the speed of the fan or fansmay be decreased or increased depending upon signals provided by thebasin water temperature sensor. In another example, the speed of the fanor fans may be increased or decreased as a result of variable processdemand wherein the operator or programmable Distributed Control System(DCS) 315 generates a signal indicating process-specific cooling needssuch as the need for more cooling to maintain or lower turbinebackpressure. In a further example, the speed of the fan or fans may beincreased or decreased by raising the basin temperature if the plant isoperating at part-load production. Fan speed can also be raised in“compensation mode” if a cell is lost in a multiple-cell tower in orderto overcome the cooling loss. Since direct-drive system 2000 providesmore torque than a comparable prior art induction motor, direct-drivesystem 2000 can operate with increased fan pitch providing requireddesign airflow at slower speeds. Since most 100% speed applicationsoperate at the maximum fan speed of 12,000 fpm to 14,000 fpm maximum tipspeed depending upon the fan design, the lower speeds of direct-drivesystem 2000 provide an airflow buffer that can be used for hot dayproduction, compensation mode and future cooling performance.

A particular geographical location may have very hot summers and verycold winters. In such a case, the variable process control systemoperates the fan in the “hot-day” mode of operation on very hot summerdays in order to meet the maximum thermal load at 100%. When the maximumthermal load diminishes, the speed of the fan is then optimized at lowerfan speeds for energy optimization. The fan will operate in this energyoptimization mode during the cooler months in order to optimize energyconsumption, which may include turning fan cells off. Since the torqueof direct-drive system 2000 is constant, the shifting of fan speedbetween maximum operation and energy optimization is without regard tofan pitch. The constant, high-torque characteristics of direct-drivesystem 2000 allow the fan to be re-tasked for (true) variable speedduty. Direct-drive system 2000 is configured to drive the fan at slowerspeeds with increased fan pitch without exceeding the fan tip speedlimitation of 12,000 feet/minute. Slower fan speed also allows forquieter operation since fan noise is a direct function of speed.Direct-drive system 2000 allows 100% design air flow to be set below themaximum fan tip speed. This feature allows for a design buffer to bebuilt into the variable process control system of the present inventionto allow for additional cooling capacity in emergency situations such asthe compensation mode (for multi-cell systems) or extremely hot days orfor increased process demand such as cracking heavier crude. Theconstant torque of direct-drive system 2000 also means that part-loadoperation is possible without the limitations and drawbacks of prior artgear-box fan drive systems.

Direct-drive system 2000 converts relatively more “amperes to air” thanprior art gearbox systems. Specifically, during actual comparisontesting of a cooling system using direct-drive system 2000 and a coolingsystem using a prior art gearbox system, direct-drive system 2000 is atleast 10% more efficient than prior art gearbox systems. Almost allexisting towers are cooling limited. Since direct-drive system 2000 is adrop-in replacement for prior art gearboxes, direct-drive system willhave an immediate impact on cooling performance and production.

The system and method of the present invention is applicable tomulti-cell cooling apparatuses. For example, a wet-cooling tower maycomprise a plurality of cells wherein each cell has a fan, fan stack,etc. Similarly, a multi-cell cooling apparatus may also comprise aplurality of ACHEs, blowers, pumps, HVACs or chillers (wet or dry,regardless of mounting arrangement). Referring to FIGS. 15A, 15B and15C, there is multi-cell cooling apparatus 600 which utilizes thevariable process control system of the present invention. Multi-cellcooling apparatus 600 comprises a plurality of cells 602. Each cell 602comprises fan assembly 12 and fan stack 14. Fan assembly 12 operateswithin fan stack 14 as described in the foregoing description. Each cell602 further comprises a direct-drive system 2000. In this embodiment,the system of the present invention includes Motor Control Center (MCC)630. A Motor Control Center (MCC) typically serves more than motor orfan cell. Motor Control Center 630 is typically located outside of theClass One, Division Two area on the ground, at least ten feet from thecooling tower. The Motor Control Center 630 is in a walk-in structurethat houses VFD device 22, DAQ device 200, industrial computer 300,power electronics and Switchgear. The Motor Control Center 630 isair-conditioned to cool the electronics. MCC 630 comprises a pluralityof Variable Frequency Drive (VFD) devices 650. Each VFD device 650functions in the same manner as VFD device 22 described in the forgoingdescription. Each VFD device 650 controls a corresponding direct-drivesystem 2000. Thus, each direct-drive system 2000 is controlledindividually and independent of the other direct-drive system 2000 inthe multi-cell cooling apparatus 600. MCC 630 further comprises a singleData Acquisition (DAQ) device 660 which is in data signal communicationwith all of the VFD devices 650 and all sensors (e.g. motor,temperature, vibration, pump-flow, etc.) in each cell. These sensorswere previously described in the foregoing description. DAQ device 660controls the VFD devices 650 in the same manner as DAQ device 200controls VFD device 22 which was previously described in the foregoingdescription. DAQ device 660 is also in data signal communication withindustrial computer 300 via data bus 670. Industrial computer 300 is indata signal communication with database 301. Both industrial computer300 and database 301 were previously described in the foregoingdescription. As shown in FIG. 15A, there are a plurality ofcommunication data junction boxes 634 which receive the signalsoutputted by the sensors (e.g. temperature, pressure, vibration). Eachcommunication data junction box 634 is in data signal communication withDAQ device 660. Each communication data junction box 634 has the samefunction and purpose as communication data junction box 111 described inthe foregoing description. The power signals outputted by the VFDdevices 650 are routed to motor disconnect junction boxes 636 which arelocated outside of fan stack 14. Each motor disconnect junction box 636has the same configuration, purpose and function as motor disconnectjunction box 106 previously described in the foregoing description.Since there is a dedicated VFD device 650 for each direct-drive system2000, each cell 602 is operated independently from the other cells 602.Thus, this embodiment of the present invention is configured to provideindividual and autonomous control of each cell 602. This means that DAQdevice 660 can operate each fan at different variable speeds atpart-load based on process demand, demand trend, air-flowcharacteristics of each tower (or fill material) and environmentalstress. Such operation optimizes energy savings while meeting variablethermal loading. Such a configuration improves energy efficiency andcooling performance. For example, if all fans are operating at minimumspeed, typically 80%, and process demand is low, DAQ device 660 isprogrammed to output signals to one or more VFD devices 650 to shut offthe corresponding fans 12. DAQ device 660 implements a compensation modeof operation if one of the cells 602 is not capable of maximumoperation, or malfunctions or is taken off line. Specifically, if onecell 602 is lost through malfunction or damage or taken off line, DAQdevice controls the remaining cells 602 so these cells compensate forthe loss of cooling resulting from the loss of that cell. End wall cellsare not as effective as cells in the middle of the tower and therefore,the end wall cells may be shut off earlier in hot weather or may need torun longer in cold weather. In accordance with the invention, the fanspeed of each cell 602 increases and decreases throughout the course ofa cooling day in a pattern generally similar to a sine wave as shown inFIG. 9. DAQ device 660 can be programmed so that when the basintemperature set-point is not met (in the case of a wet-cooling tower),DAQ device 660 issues signals to the VFD devices 650 to increase fanspeed based on a predictive schedule of speed increments based on (a)part-load based on process demand, (b) demand trend, (c) air flowcharacteristics of each tower (or fill material) and (d) environmentalstress without returning fan speed to 100%. This operational schemereduces energy consumption by the cell and preserves the operationallife of the equipment. This is contrary to typical prior art reactivecooling schedules that quickly increase the fans to 100% fan speed ifthe basin temperature set-point is not met.

The system and method of the present invention provides infinitevariable fan speed based on thermal load, process demand, historicaltrending, energy optimization schedules, and environmental conditions(e.g. weather, geographical location, time of day, time of year, etc.).The present invention provides supervisory control based on continuousmonitoring of vibrations, temperature, pump flow rate and motor speed.The present invention uses historical trending data to execute currentfan operation and predicting future fan operation and maintenance. Thesystem provides automatic de-icing of the fan without input from theoperator.

De-icing cooling towers using any of the embodiments of the direct-drivesystem of the present invention is relatively easier, safer and lessexpensive than de-icing cooling towers using prior art gearbox fan drivesystems. The capability of the direct-drive system of the presentinvention to operate the fans at slower speeds in colder weather reducesicing. The direct-drive system of the present invention has norestrictions or limitations in reverse rotation and can thereforeprovide the heat retention required to de-ice a tower in winter. DAQdevice 200 is configured to program the operation of the direct-drivesystem of the present invention to implement de-icing based on outsidetemperature, wind speed and direction, wet bulb temperature, and coolingtower inlet/outlet and flow rate. All parameters are used to develop aprogram of operation that is tailored made for the particular and uniquecharacteristics of each cooling tower, the cooling tower's location andenvironment stress.

The direct-drive system of the present invention provides constant hightorque thereby allowing the fan to operate at a relatively slower speedwith greater pitch to satisfy required air-flow while reducing acousticnoise (acoustic noise is a function of fan speed) with additionalairflow built into the system for other functions. The direct-drivesystem of the present invention is capable of infinite variable speed inboth directions. The direct-drive system of the present invention isconfigured to provide infinite variable speed up to 100% speed withconstant torque but without the duration restrictions found in manyprior art fan drive systems.

The infinite variable speed of the direct-drive system of the presentinvention in both directions allows the fan to match the thermal loadingto the environmental stress. This means more air for hot-day cooling andless air to reduce tower icing. The infinite variable speed in reversewithout duration limitations enables de-icing of the tower. Thedirect-drive system of the present invention provides high, constanttorque in both directions and high, constant torque adjustment whichallows for greater fan pitch at slower fan speeds. These importantfeatures allow for a built-in fan-speed buffer for emergency power andgreater variation in diurnal environments and seasonal changes withoutre-pitching the fan. Thus, the infinite variable speed adjustment aspectof the present invention allows for built-in cooling expansion (greaterflow) and built-in expansion without replacing any system components.The present invention provides unrestricted variable speed service ineither direction to meet ever changing environmental stress and processdemand that results in improved cooling, safety and reduced overhead.All parameters are used to develop a unique programmed, operation foreach cooling tower design, the cooling tower's geographical location andthe corresponding environmental stress. DAQ device 200 operates thedirect-drive system of the present invention in a part-load mode ofoperation that provides cooling with energy optimization and thenautomatically shifts operation to a full-load mode that providesrelatively more variable process control which is required to crackheavier crude. Once the process demand decreases, DAQ device 200 shiftsoperation of direct-drive system of the present invention back topart-load.

The variable process control system of the present invention determinesCooling Tower Thermal Capacity so as to enable operators to implementproactive service and identify maintenance and cooling improvements andexpansions. The present invention provides the ability to monitor,control, supervise and automate the cooling tower subsystems so as tomanage performance and improve safety and longevity of these subsystems.The system of the present invention is integrated directly into anexisting refinery Distributed Control System (DCS) 315 so as to allowoperators to monitor, modify, update and override the variable processcontrol system in real time. Operators can use the plant DCS 315 to senddata signals to the variable process control system of the presentinvention to automatically increase cooling for cracking crude or toprevent auxiliary system fouling or any other process. As shown by theforegoing description, for a given fan performance curve, a coolingtower can be operated to provide maximum cooling as a function of fanpitch and speed. Fan speed can be reduced if basin temperature set-pointis met. The variable speed direct-drive system of the present inventionprovides accurate cooling control as a function of environmental stress(e.g. cooling and icing), variable process control (i.e. part load ormore cooling for cracking crude, etc.) and product quality such as lightend recovery with more air-per-amp for existing installations. Thevariable process control system of the present invention allowsoperators to monitor cooling performance in real time thereby providingthe opportunity to improve splits and production and identify serviceand maintenance requirements to maintain cooling performance andproduction throughput. Furthermore, the data acquired by the system ofthe present invention is utilized to trend cooling performance of thecooling tower which results in predictive maintenance that can beplanned before outages occur as opposed to reactive maintenance thatresults in downtime and loss of production. The unique dual-bearingdesign of motor 2004, the placement of accelerometers, velocity probesand displacement probes on each of these bearings, and the vibrationanalysis algorithms implemented by industrial computer 300 allowsignificant improvements in fan vibration monitoring and provides aneffective trim balancing system to remove the fan dynamic couple. Thetrim balance feature removes the fan dynamic couple which reducesstructural fatigue on the cooling tower.

The present invention eliminates many components and machinery used inprior art fan drive systems such as gearboxes, shafts and couplings,two-speed to motors, gearbox sprag clutches to prevent reverseoperation, electric and gerotor lube pumps for gearboxes and vibrationcut-off switches. Consequently, the present invention also eliminatesthe maintenance procedures related to the aforesaid prior artcomponents, e.g. pre-seasonal re-pitching, oil changes and relatedmaintenance. The present invention allows monitoring and automation ofthe operation of the cooling tower subsystems to enable management ofperformance and improvement in component longevity. The presentinvention allows continuous monitoring and management of thedirect-drive system of the present invention, the fan and the coolingtower itself. The present invention allows for rapid replacement of aprior art fan drive system with any of the embodiments of thedirect-drive system of the present invention. The direct-drive system ofthe present invention provides an autonomous de-icing function to de-iceand/or prevent icing of the cooling tower. The system of the presentinvention is significantly more reliable than prior art systems becausethe present invention eliminates many components, correspondingcomplexities and problems related to prior art systems.

The data collected by DAQ device 200, which includes motor voltage,current, power factor, horsepower and time is used to calculate energyconsumption. In addition, voltage and current instrumentation areapplied to the system to measure energy consumption. The energyconsumption data can be used in corporate energy management programs tomonitor off-performance operation of a cooling tower. The energyconsumption data can also be used to identify rebates from energysavings or to apply for utility rebates, or to determine carbon creditsbased upon energy savings. The system of the present invention alsogenerates timely reports for corporate energy coordinators on a scheduleor upon demand. The data provided by DAQ device 200 and thepost-processing of such data by industrial computer 300 enables coolingperformance management of the entire system whether it be a wet-coolingtower, air-cooled heat exchanger (ACHE), hybrid cooling tower,mechanical tower, HVAC systems, blowers, pumps, chillers, etc.Specifically, the data and reports generated by DAQ device 200 andindustrial computer 300 enable operators to monitor energy consumptionand cooling performance. The aforesaid data and reports also provideinformation as to predictive maintenance (i.e. when maintenance ofcooling tower components will be required) and proactive maintenance(i.e. maintenance to prevent a possible breakdown). The industrialcomputer 300 records data pertaining to fan energy consumption and thus,generates fan energy consumption trends. Industrial computer 300implements computer programs and algorithms which compare theperformance of the cooling tower to the energy consumption of thecooling tower in order to provide a cost analysis of the cooling tower.This is an important feature since an end user spends more moneyoperating a poor performing tower than a tower than is in properoperating condition. This is because lower flow means more fan energyconsumption and production loss. Industrial computer 300 implements analgorithm to express the fan energy consumption as a function of thetower performance which can be used in annual energy analysis reports byengineers and energy analysts to determine if the tower is beingproperly maintained and operated. Energy analysis reports can be used toachieve energy rebates from utilities and for making operationalimprovement analysis, etc. With respect to large capital asset planningand utilization cost, a relation is derived by the following formula:N=(Cooling Tower Thermal Capacity)/(Cooling Tower Energy Consumption)wherein the quotient “N” represents a relative number that can be usedto determine if a cooling tower is operating properly or if it hasdeteriorated or if it is being incorrectly operated. Deterioration andincorrect operation of the cooling tower can lead to safety issues suchas catastrophic failure, poor cooling performance, excessive energyconsumption, poor efficiency and reduced production.

The variable speed direct-drive system of the present invention providesaccurate cooling control as a function of environmental stress (coolingand icing), variable process control (part load or more cooling forcracking, etc.) and product quality such as light end recovery with moreair-per-amp for existing installations. The present invention alsoprovides automatic adjustment of fan speed as a function of coolingdemand (process loading), environmental stress and energy efficiency andprovides adaptive vibration monitoring of the fan to prevent failure dueto fan imbalance and system resonance. The present invention allows thefans to be infinitely pitched due to constant, high torque. The built-invibration monitoring system provides a simple and cost effective trimbalance to eliminate fan dynamic couple and subsequent structural wearand tear. The variable process control system of the present inventionreduces maintenance to auxiliary equipment, maintains proper turbineback pressure and prevents fouling of the condensers. Motor 2004provides constant torque that drives the fan at lower speeds therebyincreasing airflow at a greater fan pitch and reducing fan noisesignature which typically increases at higher fan speeds (noise is afunction of fan speed). The present invention reduces energy consumptionand does not contribute to global warming. The high-torque, permanentmagnet motor 2004 expands the operational range of the fan to meet everchanging process load changes and environmental conditions by providinghigh, constant torque for full fan pitch capability. This enablesincreased airflow for existing installations, provides unrestrictedvariable speed for energy savings and reduction of ice formation, andallows reverse operation of the fan for retaining heat in the coolingtower for de-icing.

Although the previous description describes how the direct-drive systemand variable process control system of the present invention may be usedto retrofit an existing cooling tower that uses a prior art fan drivesystem, it is to be understood that the direct-drive system and variableprocess control system of the present invention can be used in newlyconstructed cooling towers, regardless of the materials used toconstruct such new cooling towers, e.g. wood, steel, concrete piermountings, pultruded fiber-reinforced plastic (FRP) structures, orcombinations thereof.

All of the foregoing embodiments of the direct-drive system of thepresent invention may be applied to HVAC systems and blowers. Therotatable output shaft of the direct-drive system of the presentinvention may be connected to any type of fan. For example, therotatable output shaft of the direct-drive system of the presentinvention may be connected to fans having a fan hub, or may be directlybolted to one-piece wide-chord fans. One-piece wide-chord fans providenoise attenuation and are best for HVAC applications. The direct-drivesystem of the present invention provides variable speed control for theHVAC system, thereby providing the requisite balancing needed by HVACsystems during dynamic weather conditions as well as energy savings.Variable speed is critical for “Intelligent Building Systems”. Thedirect-drive system of the present invention can replace centrifugalfans with axial fans including the exhaust fans on HVAC systems withvariable speed and higher pitched fans to reduce noise in sensitiveareas such as buildings. The direct-drive system of the presentinvention can be implemented to drive a variable speed exhaust fan forback-pressure control. In one embodiment, the prior art centrifugalblower of a HVAC system is replaced with direct-drive system 2300 shownin FIG. 2D in combination with a wide chord fan. The programmablefeature of direct-drive system 2300 improves cooling and energyperformance, and provides a relatively shorter package with less weight.

The direct-drive system of the present invention may also be used inpre-existing HVAC systems that are using prior art supply and exhaustcentrifugal blower fan motors. The direct-drive system of the presentinvention can be used to replace prior art condenser cooling fans, maincentrifugal fans and exhaust fans. This variable speed ETD drive systemcan be directly coupled to the fan for improved climate control, energysavings and noise attenuation. Such an embodiment also eliminates beltsand pulleys thereby simplifying installation. Such an embodimentimproves reliability, service and maintenance. In an alternateembodiment, the variable speed ETD drive system, which replaces theexhaust centrifugal blower, includes a variable frequency drive devicein order to maintain back pressure in the system.

The direct-drive system of the present invention can also be applied toexisting HVAC systems that use multiple condenser axial fans. Inaccordance with the invention, the multiple condenser axial fans wouldbe replaced with a single, relatively larger fan rotating at relativeslower speed. The aforesaid single, relatively larger fan can be of thefan-hub type configuration, or the direct-bolt configuration similar tothe whisper quiet fan (wide chord fan) described in the foregoingdescription. The single, relatively large fan is driven by thedirect-connect (i.e. direct-bolt) slow speed ETD drive system. Such asystem (a) improves air flow around the condenser (wetted area) and alsoimproves thermal management, (b) attenuates noise with slower speed (c)provides variable process control in response to climate changes, (d)provides energy savings (e) allows reverse speed for de-icing, (f)allows for a relatively smaller condenser, and (g) is reliable andrequires less service and maintenance.

The ETD drive system of the present invention can be connected to thenew, commercially available one-piece wide chord fan which operates atslower speeds for noise attenuation. One-piece, wide chord fans have nofan hub and are of a direct-bolt configuration. Thus, the fan can bedirectly attached to the output shaft of the direct-drive system of thepresent invention. The one-piece, wide chord, direct bolt fan is alsoknown as the “whisper quiet” fan which was discussed in the foregoingdescription. The one-piece, wide chord fan is relatively quieter andoperates at a relatively slower speed than conventions fans.

Referring to FIGS. 27 and 28, there is shown a HVAC system that uses oneembodiment of the direct-drive system of the present invention. HVACsystem 6000 has main structure 6002 and support structure 6004. Directdrive system 2000 is connected to support structure 6004. Direct drivesystem 2000 drives axial condenser fan 6006. Fan 6006 rotates within fanstack 6008 which is connected to and supported by main structure 6002.Plenum volume 6010 is located below fan 6006 and is within mainstructure 6002. Condenser coils 6012 are located within plenum volume6010. HVAC system 6000 also includes an axial fan system, generallyindicated by reference number 6020, which comprises fan 6030 anddirect-drive system 2000. In this embodiment, direct-drive system 2000and fan 6030 are configured as an axial fan system which would replace acentrifugal fan. Direct-drive system 2000 is mounted to supportstructure 6040. Support structure 6040 is connected to the interiorwalls of main structure 6002.

Referring to FIG. 29, there is shown centrifugal fan system 7000 whichcomprises centrifugal fan 7002. Direct-drive system 2000′ drives fan7002. Fan 7002 rotates within housing or duct 7004. Direct-drive system2000′ has generally the same structure and design as direct-drive system2000 shown in FIG. 2B except rotatable output shaft 2010 is replacedwith a substantially longer shaft 7010 which functions as the fan shaft.This fan shaft 7010 is supported by the motor output bearings at themotor end of direct-drive system 2000′. Thus, in this embodiment, thefan is solely supported by the load bearing motor of direct-drive system2000′. In an alternate embodiment, an additional bearing 7011 is addedat end 7012 of shaft 7010 for additional support.

Referring to FIGS. 30 and 31, there is shown centrifugal fan apparatus8000 that utilizes direct-drive system 2000 of the present invention.Centrifugal fan apparatus 8000 comprises housing 2002 and centrifugalfan 8004. Centrifugal fan 8004 comprises fan hub 8006. Direct-drivesystem 2000 is positioned within the interior of housing 2002 and isattached to section 8008 of housing 2002. Shaft 2010 of direct-drivesystem 2000 is connected to fan hub 8006. Accordingly, the variableprocess control system as described herein is used to control operationof centrifugal fan apparatus 8000. In this embodiment, the load bearingdirect-drive system 2000 solely supports the cantilever fan.

Referring to FIG. 32, there is shown an alternate embodiment of thecentrifugal fan apparatus shown in FIGS. 30 and 31. Centrifugal fanapparatus 9000 comprises housing 9002 and centrifugal fan 9004.Centrifugal fan 9004 comprises fan hub 9006. Direct-drive system 2000 ispositioned within the interior of housing 9002 and is attached tosection 9008 of housing 9002. Shaft 2010 of direct-drive system 2000 isconnected to fan hub 9006. Bearing 9010 is mounted to housing 9002.Shaft extension 9012 is connected between fan hub 9006 and housing 9002.In this embodiment, bearing 9012 and load bearing direct-drive system2000 support the cantilever fan.

The direct-drive system of the present invention may be applied toapplications other than cooling towers, HVAC systems, blowers orchillers. For example, all of the embodiments of the direct-drive systemof the present invention may be used in other applications includingwindmills or wind turbine generators, paper machines, marine propulsionsystems, ski-lifts and elevators.

The present invention is also applicable to steel mills and glassprocessing, as well as any other process wherein the control of thetemperature and flow of cooling water is critical. Temperature controlof the water is crucial for cooling the steel and glass product toobtain the correct material composition. The capability of the presentinvention to provide constant basin water temperature is directlyapplicable to steel mill operation, glass processing and resultingproduct quality and capacity. The capability of the direct-drive systemof the present invention and fan 12 to operate in reverse withoutlimitation allows more heat to be retained in the process water on colddays. This would be accomplished by slowing the fan 12 or operating thefan 12 in reverse in order to retain more heat in the tower and thus,more heat in the process water in the basin. The variable processcontrol system of the present invention can deliver infinite temperaturevariation on demand to the process as required to support production andimprove control and quality of the product.

While the foregoing description is exemplary of the present invention,those of ordinary skill in the relevant arts will recognize the manyvariations, alterations, modifications, substitutions and the like arereadily possible, especially in light of this description, theaccompanying drawings and the claims drawn hereto. In any case, becausethe scope of the invention is much broader than any particularembodiment, the foregoing detailed description should not be construedas a limitation of the present invention, which is limited only by theclaims appended hereto.

What is claimed is:
 1. A drive system for rotating a fan in a wet or drycooling tower, comprising: an epicyclic traction drive device includinga rotatable output shaft that is configured to be attached to a fan in awet cooling tower or a dry cooling tower; an electric motor comprising arotatable shaft and a sealed bearing system, wherein the rotatable shaftof the electric motor is connected to the epicyclic traction drivedevice such that the rotatable shaft of the electric motor drives theepicyclic traction drive device and causes rotation of the rotatableoutput shaft of the epicyclic traction drive device, the electric motorincluding an input for receiving electrical signals; and a programmablemotor controller in electrical signal communication with the input ofthe electric motor and configured to initiate rotation of the rotatableshaft of the electric motor in accordance with a pre-programmedacceleration rate and to slow the rotation of the rotatable shaft of theelectric motor in accordance with a pre-programmed deceleration rate. 2.A drive system for rotating a load comprising: an electric motorcomprising a rotatable shaft and a sealed bearing system configured toallow the motor to operate in a forward direction or reverse direction;an epicyclic traction drive device including a rotatable output shaftthat is configured to be attached to a load, the epicyclic tractiondrive being engaged with the rotatable shaft of the electric motor so asto allow the electric motor to drive the epicyclic traction drivedevice, the epicyclic traction drive device including a brake mechanismto brake the epicyclic traction drive device, and a programmable motorcontroller configured to initiate rotation of the rotatable shaft of theelectric motor in accordance with a pre-programmed acceleration rate andto slow the rotation of the rotatable shaft of the electric motor inaccordance with a pre-programmed deceleration rate.
 3. A drive systemfor rotating a load comprising: an electric motor comprising a stator, arotor, a rotatable shaft and a bearing system configured to allow themotor to operate in a forward direction or reverse direction; anepicyclic traction drive device including a rotatable output shaft thatis configured to be attached to a load, the epicyclic traction drivedevice including a sun roller that engages the rotatable shaft of theelectric motor so as to allow the electric motor to drive the epicyclictraction drive device; and a programmable motor controller configured toinitiate rotation of the rotatable shaft of the electric motor inaccordance with a pre-programmed acceleration rate and to slow therotation of the rotatable shaft of the electric motor in accordance witha pre-programmed deceleration rate.
 4. The drive system according toclaim 3 further comprising means to brake the epicyclic traction drivedevice.
 5. The drive system according to claim 3 further comprising abrake mechanism to brake the epicyclic traction drive device.